Hi April & a belated welcome!,
My recommendation is that you get one conical and one straight bore whistle. Foir conical, I’d recommend a Meg or Sweetone, as they are the easiest whistle for a beginning whistler to play - though some don’t like the tone. A Clarke Original would take a little more air, and a Shaw is a possibility if you’ve good lungs and need to get rid of that air quickly!
For Cylindrical Bore, the Generation (get a brass one with red or green top) would give the most traditional Irish sound, if that’s what you want. A Walton or Feadog is equally as good. There is a Walton Mellow D with a wider bore also designed for a mellower sound, which is very popular.