I guess I have some knowledge on various brands that I have seen. I have to say that Horton brand is ok but probably the loudest crossbows I have ever been around. Excalibur is a crossbow with a recurve style limb, no cams. Its definetly the quietest and one of the fastest. Ten Point is an excellent brand but is the most expensive I have seen yet. I know they work well with hunters with handicaps. I have had two people hunt with me recently that use one of their bows and they performed flawlessly and deadly out to 45 yards.
The scopes that come on some of them are one of the biggest issues with most of the hunters I have seen using them. Some like the red dot scopes and some dispise them. If you get one with a red dot, make sure you remember to turn down the intensity of the light the darker it gets outside because if you don't you will find your target is blurred by the bright red light. Most scopes I have seen have an adjustment for the intensity of the red light.
Another thing to pay close attention to when buying a crossbow is the cocking device. Some bows you still have to have a good strong shoulder to pull the string back with both hands. Others have a crank. Some have a rope you can use to help pull.
When you @#)(# the string back some bows go automatically to safety. Others remain on fire. This is something you need to be aware of and be very carefull with.
Ten Point is the only crossbow I know of that has an adjustable trigger. That may be something you can look into as well.
Parker is supposed to make an excellent crossbow but I have yet to have anyone come hunt with one. From what little I have read and seen about them, they look like a solid bow and a good product.