Its really hard to say...depends completely on what fits the horse best, and of course they are all different. I'd suggest looking at a treeless option or adjustable tree if the horse is still growing.
I personally hate wintecs...but its just a personal opinion. The synthetic aspect just turns me off and they seem to run narrow and small (for both horse and rider).
I've owned a Stubben all-purpose, a County dressage, and a Crosby all-purpose. Liked them all. But that doesn't really help you decide what will be comfortable for your horse and you:P