For the first time in 20 years I am looking to buy a new MTB. Looking at the various brochures and websites it seems that things have changed a little from when I last looked. It seems to me that there are 2-3 subcategories within the MTB field now. With full sus downhill bikes, hardtails and others, then all sorts of excitement and argument over wheel sizes I already have a what I call commuter bike, with skinny tyres which i use for well, commuting and general nipping to the shops and on road / cyclepath stuff. What I want is a MTB that I plan on using this bike for general off road stuff, be that the muddy tracks and routes around the local park (anything where the commuter wheels are two thin) or be it riding around the rocky trails and downhill sections of the Lancashire Hills. I am of the mindset that going/getting up the hills are as much part of the fun as going down and are not seen as just an inconvenience. Being 5'9" I am thinking that 650B wheels will be the sensible choice for this bike? Budget will be around £600 - 1000. Second hand will be considered. What sort of thing should I be looking for?