I have a Bon Tee in A, and it's been my go to box lately. Most songs I play are on the pull, which is of course the key of E. And yep, it's definitely an easier key to sing in than a C, and much easier than a D.
I'd like to have a nice G - that's even better than A for singing. I should see if I could make a trade to get one.
I don't really have an opinion about the types of reeds. I have 8 cajun accordions (1 A, 3 Bb, 3 C, 1 D), and they all have Binci reeds. Seems OK to me. But I don't have a high E or F so I can't comment on that.
As to who makes the best accordions for Zydeco, well, there's really no difference between the accordions used for Cajun Music and those for Zydeco. For Zydeco, we like internal mics, while external mics are more common for Cajun music. But the accordions themselves are the same.
There's a weird myth that for Zydeco accordions "must" be tuned wet, and for Cajun accordions "must" be dry, but there's no truth to that.
I think the internal mics used for zydeco music might make the accordions sound wetter, so maybe that's where the myth came from. Other than that, the choice between wet and dry comes down to personal preference. Rules are for fools!
Never heard of Brescia reeds. Can you elaborate on those a little?
One thing I'll say about Hohner reeds, there are some that, to my taste, are my favorite sounding reeds of any of them. But since, like the old German reeds, they are/were made by so many sources, the quality is very inconsistent. The old ones, if you can find them, are usually good. I don't have much confidence in new ones.
Not sure what that might be. Only other reeds I know of being used are Voci Armoniche, which I don't care for, and Antonelli.
You won't find old Hohner or old German made reeds except by pure luck. If you're wanting mellower, the Harmonikas reeds are definitely mellower. They have several options, I've tried 3 different versions of their reeds, all different sounding. Never tried higher than D, though.
I stumbled on a pre-Hohner German accordion made by Koch, probably early 1920s. 3-row box, F, B-flat, E-flat, two reeds per note. I didn't think about repurposing the reeds, but this thread has me thinking. Link #1 is an overview of the instrument by a local repair tech who restored it, Link #2 is his shop, Link #3 is Scott's YouTube page. He teaches engineering, and has an amazing setup for repairs.