Since we are working from our own definition of “best”, I’ll put my lineup in the mix, from high to low.
Generation F - Basically a kid’s toy. Screechy, finicky, useful only for annoying family and dogs.
Killarney Eb - Very pure in sound, takes almost no air. Because of the air requirement there is the constant challenge not to overblow and ruin the sweet clean sound. Without any chiff or airiness in the sound, this whistle sounds really screechy to me. Maybe this is a good one for recording sessions? In a live session it would disappear at the low end and the high end would sound like someone beeping buttons on a cash register. I never play this.
Overton/Goldie D - What a sweetheart of a whistle! Though just a half step below the Killarney it sounds like a much bigger and lower whistle, with just enough airiness to give it backbone. This one can take all sorts of blowing volume and still perform. Somewhat quiet on the bottom few notes but such a solid performer, and it does everything you ask of it. Sometimes you get what you pay for and this is just in a separate league from cheaper whistles.
Dixon Pro D - Now that I have the Overton D, this one has a screechy edge that I dislike. It’s louder on the low end but that sharp edge makes it sound annoying. Not as forgiving in changes in air volume.
Feadog D brass - One of my first and favorite whistles. Better, I think than the Dixon Pro which was five times more expensive. Tunable, clear, responsive, I gave it away to a friend to get him started on whistles. Not in the same realm as the Overton D but a darn fine instrument.
Chieftan Thunderbird C - This whistle can knock it out of the park. Loud, bright, responsive, and can take big shifts in air volume. Like the Overton it can be played loud or quiet with a large dynamic range. The Killarney, with such low air requirements, has a really small dynamic range. So if you want to sound haunting and airy, then strong and bright a few seconds later, this is the whistle. The Killarney can pretty much do one tone quality only. Not a knock on it, but you’d better like that one tone quality because you can’t change it by how you play.
Generation C - Like its smaller cousin above, this sounds like a toy. I’ll bet with some tweaking and reengineering this could be a pretty good whistle. For people who want to build and modify whistles this is a good place to start. I want to play whistles so this sits in a drawer and is brought out to fiddle on for a few seconds. Then it goes away.
Chieftan Thunderbird Bb - In comparison with the C it’s much quieter and more airy. I love this whistle for slow airs. I don’t know if there is such a difference between Thunderbirds in keys but this is a sibling to the C but not a twin.
Shearwater Bb - Don’t have this one any more but I have to respect it. Unbelievably quiet, airy, and evenly tuned through both octaves. It took a TON of air and sounded like a sigh through crushed velvet. It would be amazing for studio work but didn’t meet my needs.
Susato A - Sold this one as well. Kind of reminded me of a Ford Taurus - dependable and forgettable. It had an unrefined plastic brightness to the tone and the top octave seemed twice as loud. Once it had enough air it went fine but didn’t have as much dynamic range as the Goldies. And it looked like a clarinet.
Goldie A - My favorite whistle. Some of that is the key, which is high enough to be heard through anything and low enough to have some real character and body. It’s fantastically dynamic, can play with the slightest breath and punch through background noise if it needs to. This is like five whistles in one and if I could only have one whistle the rest of my life this would be it. But…it’s so prone to clogging that it needs a couple drops of sodium lauryl sulfate down the mouthpiece every second or third session. Small price to pay, I think.
Kerry Optima F - I really love this whistle. Airy, big round sound, responsive but not edgy. It takes a ton of air and can be pushed to do a lot. Imagine a Crown Victoria–big, powerful, and can haul a$$ when a cop is driving it. Sure, it’s not a McLaren but isn’t meant to be. And the dished holes make it easier to go fast and not improperly seal a hole. I wish more makers would do this, especially on low whistles.
Goldie F - Again, this whistle is just in a different category. It takes much less air than the Optima but can seem to do more. It’s more responsive on ornamentation, more balanced in volume and tuning between octaves, and just sounds like a finer more upright instrument than most. It represents, sorry for the pun, the Goldie Standard.
Kerry Optima D - This one’s a bit more wobbly than the Optima F at low range. I know this is a hard thing to get right on low whistles but the bottom few notes just disappear in airy mudiness. It takes big lungs, and be prepared for a sound like a ghost blowing across the moors. Lovely but not always what you’re after.
Overton D - I heard someone call the Overton sound a cosmic drainpipe and I understand that with this whistle. It’s got a kaleidoscope of overtones and richness throughout both octaves and can be quite clear and nimble for such a low whistle. Good luck reaching and covering the holes if you have small hands, but figure out your hand position and piper’s grip and you’ll be rewarded big time!
There you have it, my own take on what I like. Again, some people might want bluebird chirpiness or haunting airiness. Coming from a background of saxophone and bagpipes I like to use my lungs so want whistles that you can really work out. Now get out there and play!