The Knight & Hale UHT 001 was my go to diaphragm and has helped seal the deal on more than a few gobblers since it was introduced. I buy 6 of them at a time because they are no longer sold individually, so you have to order 6 at a time from the factory.
I'm using more Tom Teasers calls these days too. I got a dozen from Tommy at the Dixie Deer Classic in Raleigh earlier this month. His Cracked Corn diaphragm does a great Kee Kee and yelps just as well. Tom Teasers Teaser Pleaser sounds real good and their Redneck Hen talks the talk and walks the walk. I have called in several gobblers with the Redneck Hen since I started using it about 5 years ago. Those are my favorites right now.
Some diaphragms are hard to get a good seal or a good fit against the roof of my mouth. There's some calls that sound horrible in my mouth, yet a friend can make the same model sound great. Find ones you can get good sound out of, stick with 'em. Buy an extra or two so you have a spare if you need it. They store well in the freezer and don't deteriorate like if left in the open or in a sunny spot.
I take the calls out of my vest at the end of the season and use them for practice during the year until they give up. Then, I break in new ones before the season so they're ready and I know what to expect out of each one when it counts.
Luck Counts, good or bad