Quality-wise, of those three the Ayr would be the best leather and best workmanship. And it has "hybrid" mostly flocked panels with a little foam an you can adjust the fit by flocking. The Ovation is made in Argentina by Ruiz Dias who used to make the Collegiate brand when Miller Harness still owned that name. RD on a saddle means Ruiz Diaz. I haven't seen an Ovation to know what their leather looks like. Offhand I don't know whether their panels are available flocked.
Weatherbeeta owns the Collegiate name. Some or all of them are made in Vietnam and their leather is not the highest quality and tends to scuff a lot. If you want a Collegiate Convertible, you can pick one up used on eBay
for $500 to $600 used or same price on Craigslist and that might get you the whole gullet set along with fittings, too. Sometimes you can find a used Bates Caprilli cc for $800 - $850.
The Wintec/Bates/Collegiate cc tree is curved / has rocker / is banana shaped. All that the gullet change does is change the width and angle of the front of the saddle. That curve (sway) of the saddle tree has to match the shape (sway) of your horse's back. Sway isn't the right word but I knew it would help you picture what I'm talking about. Generally a wide horse will be wide all the way back the body. And that saddle tree with the white XW gullet might be wide enough at the front but will be too banana shaped for a wide horse that has a broader and flatter back.
Collegiate Diploma and its predecessor the Varsity are flocked panels. Not sure about the Alumni. The Diploma always looks like a more forward flap to me, than the Alumni.