I have finally decided to move up in the world to a higher priced penny whistle. I have decided on a Burke. My issue is material. From an historical stand point what generally sounds best. I have no chance to try one and the sounds on the websight are never accurate. The decision is Brass, aluminum, or wood fiber composite. Any thoughts or personal recommendations? Any advise would be helpful. Many thanks.
Before you buy Burke, I would highly recommend looking into Dixon’s higher-class models. I had the chance to play a Burke brass narrow bore and one of the thick-walled brass Dixons, and I was super impressed with the Dixon. I still think Burke really favors the low octave at the expense of the upper octave, and where the Burke started to get shrill, the Dixon was still sweet and a little breathy in the upper octave, which was very pleasant on the ears. Still nice and strong in the low octave. Dixons are quite a bit cheaper and have a slightly more traditional sound, but you make up your own mind. Play a few if you can. Find a music store near you that carries whistles and browse, browse, browse.
If you do go for the Burke though, brass narrow bore all the way. His session-bore whistles are just irritating in the upper octave.
It really depends on a number of factors including what type of tonal qualities you are seeking, how long you are willing wait for a maker to fill your order, what key you are looking for, your budget, etc., do you need a tuneable or do you only play alone, what volume and air requirements, the list goes on.
Michael Burke makes some great whistles along with a number of other makers of great whistles. Do your homework, make a list of what you are looking for in a whistle, and go for it.
Enjoy the hunt for your new whistle lad, it’s fun. 
Cayden
Sure I have a recommendation. Buy one of each.
Assuming we are talking about high D’s here. Is that right? I own and play Burke D’s in all three materials and both bores. They are all extremely good whistles, well designed, well made and nice sounding. Playing characteristics are very good, as good as on any whistle I have owned and better than most (YMMV). They are very predictable whistles and well balanced regarding volume and breath input.
Materials do not matter much in the sound of the whistle. It is more a matter of design and construction. The design of all the Burkes are as similar as Michael Burke can make them. The Burke brass and aluminum whistles sound very similar. I doubt anyone could tell the difference between them in a blind listening. The player will notice a a bit more roundness or ringing in the brass model compared to the aluminum. But they sound the same to listeners and microphones. The composite models are a bit more mellow.
In any case you will not be dissappointed. They are very good whistles.
Feadoggie
Michael Burke’s website used to be full of sound clips… don’t know if it still is. If so, that’s the best path to take for your answer… we can’t tell you what will sound best to you.
The choice in material for whistles, generally speaking, has been a long-debated topic on this forum… One that resurfaces every so often and usually results in an agreement to disagree on the matter - That is, some hear a distinct difference from one type of metal to another, and some hear little to none. In the camp that believes they hear a difference they often remark that aluminum sounds brighter, whereas brass has a mellower, warmer tone. Both camps generally agree that wood is in a class of it’s own, along with many polymers, and are the mellowest sounding of all the materials from which a player may choose. Burke’s third option would obviously fall into this category.
I personally believe that the player can and does have a substantial affect on any whistle’s tone. While I am perfectly agreeable that different whistles can be and often are inherently different from each other with respect to tone (and this is especially true with Burke whistles, which are very pure-sounding to most), I don’t think one should discount the impact an individual’s playing style and level of ability can also have on the same whistles respectively… or as I have often put it in the past, I judge a whistle based on how it sounds in my hands, not in someone else’s. 
I’d also echo Feadoggie’s sentiment… Burkes are very nice whistles.
Full of sound clips as it may be, whistles are subject to extreme variance in tone depending on the recording method. The only way to be sure is play one, unfortunately. You can get an idea via a sound clip, but they can be surprisingly inaccurate to the actual sound. Burkes are excellent quality whistles, to be sure, and I love my narrow bore brass, but for solo playing the upper octave just doesn’t do it for me. The thickbody brass Dixon on the other hand, has a bit more air-noise in the upper octave that softens it even at the high B. Both whistles are excellent choices, and it really comes down to what you prefer. I gravitated towards the Burke narrow bore because I wanted a whistle with a warm tone and a sweeter upper octave, but it was still a little piercing (likely as a tradeoff for the extra volume needed in sessions). So the Dixon does it for me solo, but the Burke is my sessioner.
On the subject of materials, the only clear trend I’ve noticed in metals is that thickness, not material, tends to have the most influence over the tone. I think the reason many say brass is mellower is because on most brass whistles I’ve played, the material has been generally thicker than the nickel and aluminum whistles. Take for example Generations, sold in brass and nickel. Scrape some of the plating off the nickel Gen and guess what? It’s brass underneath, just thinner than the unplated whistles. It’s the only thing that could account for the difference in sound assuming the headjoints are the same. I played a Dixon thickbody aluminum C the other day and it was darker even than my very dark brass A.
Buy a Burke. You will be very happy with any one you choose.
Why is it that when someone starts their thread by saying they have decided to buy whistle XYZ that we have to contradict their very likely well considered decision and suggest brand QST instead?
The OP could have decided on a Dixon and asked for advice on materials. But they didn’t ask about Dixons.
I cannot see any way that a Burke narrow bore is “piercing” or that a Burke session bore whistle is “irritating”. Well … there is the matter of the individual player but that’s not the whistle’s fault.
Sorry about the rant.
Feadoggie
I usually wouldn’t suggest a different brand when someone asks about one, but in this situation I thought I’d share a personal experience that might help refine saintjb’s decision. I got a Burke because I wanted a rounder, sweeter sound especially in the higher octave. Up to about high G the whistle is absolutely my favorite of all I have, but those last two notes get a little shrill to my ears. Since saintjb has decided on Burke, it may be possible he is looking for similar tonal qualities to the ones I was. I found that at least for solo playing, the Dixon suited those needs better. The advantage with Dixon is that they’re fairly common and so it’s possible to try before you buy. If it suits you, you can walk out of the store that same day with a whistle.
Again, I’m only providing my subjective experience that saintjb is free to ignore. More information is always better. I’m not trying to malign Burke, far from it I think Burkes have some incredible strengths and I certainly wouldn’t part with mine, but it didn’t quite do what I was hoping it would when I was looking for a new whistle.
Granted, I am extremely picky about my high Ds (in case you couldn’t tell already). I often play in the residential areas of my school, so I tend to be more conscious of volume and shrillness, though that may also be a function of my fairly sensitive hearing. As I play more and more in the local session though, I’m leaning increasingly heavily on my Burke.
I have to disagree with you there. The session bore aluminum was not a good choice for me. (again, my subjective opinion).
Saintjb,
You don’t say where you live but both The Irish Flute Store and Whistle and Drum offer a return/trial period so you could buy all three and return any that don’t suit. I’ve done that, and it removes all of the doubt. There’s nothing like actually having the things in your hands, not to mention, mouth.
JD