Tyres are an expensive nightmare until you find the ones you like. What may work for me, and the trails I ride, may not suit you at all, and vice versa. Not many tyres are good at varied terrain either, so this needs to be taken into consideration… Do you want several very specialist tyres, or one set that are a jack of all trades? Then you must not forget construction. Some people get on fine with paper thin sidewalled tyres like Schwalbe Rocket Ron’s, some people ride dual ply Maxxis on their XC bike.
It’s all a compromise. The thing is, finding the best compromise for you.
Personally, for me, it’s the Conti Rubber Queens in 2.2″ flavour. They’re massively expensive yes, but they really are exceptionally good at pretty much most things I’ve found. Just not particularly quick, so if you do a lot of road riding, or hardpack, then something faster (at least on the back) would suit better.