It's mainly quality, I have been up many loft ladders, you get what you pay for, some are well made such as solid, with or without handrail, some are bendy, some of them are awkward to pull down, some slide better than others! some are heavy therefore can be dangerous if you let it go!some are too narrow or not comfortable to step on. some of them have to open the trap door first then pull the ladder down etc. It's nice to have choices but the biggest problem I find is not able to try it out unless recommmended by a friend. My local loft shop have some on display to try out
ps: the most important is make sure there's plenty of headroom for the ladder to swing in without hitting the rafters