[masatisan]

It depends very much on your price point. For changable gullets the best by far is Bates (leather) or Wintec (synthetic). An all purpose would probably be the best. Bates/Wintec just released their new models and they look like the gullets would be super easy to change.

This is their new one:

This is the older version that I have:

 

[CaptainLiecy]

go wintec 2000! i have that one and the gullet is super easy to change. also my wintec 5000 dressage is really good too but my jumping one that i dont use much is really hard because the screws are shorter
i personally think the new wintec range is pretty ugly. they look too bulky to me

 

[makin tracks]

I'm not a lover of synthetic saddles. However, I do have a Wintec 2000 which is about 10 years old and I love it.

I haven't used their jumping saddles though I know a few kids who think they are great.

I think, though, a lot of recent models in various brands can have their gullet changed by a saddler - not necessarily easy but do-able.