Obviously I'm an endurance rider, so that's the area I'm most experienced. I think any of the Ghost models would be comfortable on the trail. The Barroco might be a little fancy looking, but hey, on the trail, do what feels right! If you want to look a little more western, I'd suggest the Western saddle or a brown or two-tone saddle in either the Quilty or Quevis models with fenders. You can ride these saddles without the fenders and endurance riders might consider this to save on weight. If you already have a treeless pad, it's likely it can work with Ghost. I've tested several for shape and support suitability, so if you're wondering, just ask. The Ghost pad is a great pad, especially for the price. But endurance riders might also consider Skito, Grandeur, Toklat Matrix or others.
The Roma and Lipica are the best options for dressage riders with a long, straight leg. And of course the classical black looks great. If you have a longer thigh and need a bit more angle in your leg, the Veneto can work as well as the Lipica. If you are competing, you can't have an open gullet for dressage, so choosing the hidden pommel will solve this.
The Veneto and Classic Italy will allow a shorter stirrup for Hunter Jumper classes. For casual riding, any of the long flap models will work and then you can have lots of fun with colors and materials!
I'd love to hear stories of people jumping with theirs Ghosts. I've only done about 18" so far because I don't have any horses interested in jumping right now. The jumps I've taken were in the 17" Roma and I didn't have any problems with no having shortened my stirrups - well, at 18", we barely did a hop! I also took a few in an 18" Quevis which was too big for me, but I had my stirrups forward and we had some lovely canters out of the hops. I'd recommend the Veneto or Italy in general. We don't recommend jumping high or frequently in a treeless saddle, but with the latest panels I would definitely do the occasional low level pair pace or hop logs in the woods. We do have some customers foxhunting in Europe.
The Ghost USA/Western saddle is fairly new to Ghost, but it is a lovely saddle which can be ordered with or without horn or thigh blocks. Even the seat skirting is removeable so if you want to keep the wool beautiful for showing, you can take it off for general riding. The Ghost USA still has an english feel to the seat with a comfy twist, something you're not going to find on many other western saddles
In Europe, riders aren't as pressed to have a fancy western saddle for gymkhanas so even the Quilty/Quevis models have been used for running barrels. They are remarkably stable on many horses but I'd still recommend a breast collar which they aren't as used to in Europe!