Consider what you are doing with the saddle. You would never rope steers with a 25lb saddle. And a treeless or a saddle built on a light weight tree would not hold up to the stress of steer hitting the end of the rope. But for a trail saddle they will do the job. I have a "Specialized Saddle" that weighs 28lbs. It has pads and shims made of rubber that are very easy to change to fit what ever horse I put it on. It has held up great for 10 years of use and my daughters love to use it since it's so light to lift up and put on the horse. But it's a lousy saddle for me to throw a saddle pannier over the top and try to pack anything.
If you are roping you want something that's easy to get out of. When they get the calf roped those cowboys want to hit the dirt running to get it tied up. As a trail rider, I like a little more security. I want the saddle to hold me in, if the horse I'm riding spooks and jumps away from what ever spooked him. A saddle with a little higher cantle and pomel will help hold you in. If you are breaking young horses that have a tendency to buck, then you really want a bear trap of a saddle to keep you in place.
Do you plan to carry a lot of stuff with you on trail rides? A bigger skirt helps to support and spread the weight of saddle bags. If you rarely carry much weight while on a trail ride, the smaller rounded skirts give the horse more freedom of movement. Is your horse gaited. Some of the gaited breeds need more shoulder movement than the stock breed horses do. The gaited horse saddles usually cut the front skirt back some to allow more shoulder movement.
Do you want a padded seat or a slick seat? I prefer a slick seat, but there are a lot of folks who want to sit on a soft padded seat.
Tucker Saddles are probably best known as a trail saddle, Look at their website and see what features they stress for their trail saddles and use that as a guideline for what you consider. New quality built american saddles will sell for $1400 to $2000 with custom saddles going for more than that. I see Mexican saddles at the tack auctions going for $300 new. You know that their is something missing if they can sell them that cheap. The quality saddles have chrome tanned leather, the mexican saddles have who know what kind of tanning in the leather. The thickness of the leather is half as thick in the mexican built. The quality of the tooling, how many stitches per inch and the type of thread used on the sewing. A good quality saddle will last your lifetime, a cheap saddle will last 2-3 years.
You can find quality saddles selling as used saddles and would be better off than buying a cheap new saddle. As mentioned Crates, Colorado Saddlery, Heford are production saddles built in mass quanities that use good materials and will last a long time.
And understand that not every saddle will fit every horse. Saddles come with Quarter horse bars, Semi Quarter horse bars, Arab bars etc. Buying the wrong saddle can make you horse very sore. I would be hesiteant to buy a saddle mail order and just expect it to fit my horse. I like to set the saddle on the horse and see how it fits his back. I've been known to buy a good saddle in a pawn shop at a great price and when I got home and set it on the horses back, saw that it wouldn't fit and that saddle has often sat in my tack room waiting for a horse whose back it would fit.