Whatever saddle you get must fit you AND the horse. You don't mention if you are riding different horses or have your own horse. If you are riding different horses, don't buy a saddle yet OR buy one that fits the horse you ride most often and do not use it on any other horse.
If you are buying a saddle for one horse, invest in having a qualified saddle fitter come out to make tracings of your horse's back and recommendations for the best type of saddle for your horse. The tree of the saddle must be wide enough (but not too wide) for your horse's shoulders without interfering with the shoulder movement. It also has to be the right shape for your horse's back. Some horses have straight, flatter backs. Some backs have a curve that drop down from the withers and then back up again towards the loins. These require different shaped trees. There also has to be enough space between the panels so that there is no pressure put directly on the horse's spine. There is lots of information available online about correctly fitting a saddle. Check out Schleese Saddlery
for some excellent tutorial videos.
The saddle also needs to fit you correctly so that you are balanced and able to maintain the correct position comfortably. If the saddle is too wide or too narrow in the twist, then you will not be comfortable. If it is too high in the back it will pitch you forward. Too high in the front and it will make you lean back too far. An unbalance rider cannot be an effective rider and will also affect the horse's balance.
The last recommendation is to look for a saddle that is wool or felt flocked (stuffing). Avoid foam filled saddles if possible. A wool or felt flocked can be re-stuffed and adjusted to fit the horse as his shape changes with training or age. The foam is saddles cannot easily be replaced. So the saddle cannot be adjusted. Eventually, the foam disintegrates and does break down into fine crumbles so there is no protection for the horse's back.
Well made saddles hold their value over time. Look for a well made, well known brand of saddle - even buying a used one that fits your budget, your horse and you will be money better spent than on a brand new, lower end saddle that does not fit properly.