I’d find a tack shop that had some used ones and go sit in them. They’re both pretty well known brands and hold up decently well from what I’ve seen, but without knowing your exact body conformation and the conformation of your horse, it’s going to be very difficult for anyone on here to give you a hard-and-fast answer. If you need recommendations for forward/straight flap, a photo of you sitting in your current saddle will probably help.
As far as fitting a number of horses - I’ve heard that many of the “adjustable” saddles just aren’t the panacea that a lot of people hope they will be. If the interchangeable gullet system is the only reason you’re looking at those two brands, you’d probably be just as well off buying a saddle without the gullet systems, but fits YOU better and is generally suited to the types of horses you find yourself riding most frequently. Then, just shim as is appropriate for the horse you’re on. Basically, if you can’t adjust the fit well enough with just shims, you probably won’t be able to adjust the gullet on an interchangeable one any better either.