I have a synthetic dressage saddle and a leather one. I absolutely HATE the synthetic - I use it on my breaker because it's almost impossible to fall out of [I've come out of it 3 times] but once she's a bit more broke, and a bit more mature physically, I'll be getting her something really nice. I'm in love with Black Country saddles [can't remember which model I sat in but it had textured leather, not smooth], so I'm really hoping to be able to find one of those, but a KN would be nice, or a second hand Bates. I'm not a fan of the latest model Bates saddles but have ridden in a Caprilli Show that was absolutely divine, two Innovas which I found so easy to ride in, and an Isabell. All second hand; I wasn't a fan of the Isabell but loved the others.
Don't bother with all purpose saddles. They're only good for people who want to do a bit of everything and can't afford two saddles, or for people who don't know what they want to do. I am primarily a jumpers rider, but I do event and dabble in dressage and show hack classes, so I have chosen to buy dressage saddles and jumping saddles rather than a saddle that is made to "do everything". The all purpose is a jack of all trades, master of none.
I am 5'1 and petite. I weigh less than 110 pounds sopping wet, in full riding gear. I ride in a 17.5 inch saddle, given the choice. My lovely Stubben close contact dressage is only a 17 inch and is a touch on the small side for me but is beautiful, fits my horse, and was cheap. I own six saddles and every one of them is either 17 inch or 17.5, bar one 16.5 inch all purpose. However, I know someone who is 5'8" and rides in a 16 inch saddle. It's all about your body shape, and the length of your thigh. Mine is very long, so I need a fairly big saddle.