Choosing a hardtail from J E James

Minty88

As I'm getting a bike through work I'm looking at J E James as its my local bike shop and I want to try a few bikes out before I choose. I've whittled it down so far to

http://www.jejamescycles.co.uk/diamondback-apex-mountain-bike-id70336.html

or

http://www.jejamescycles.co.uk/orange-g3-mountain-bike-grey-id58454.html

http://www.jejamescycles.co.uk/specialized-rockhopper-comp-mountain-bike-black-green-white-id65393.html

http://www.jejamescycles.co.uk/focus-black-hills-mountain-bike-id65663.html

I was going to try at least a couple when I get a chance to go in but is there one that particularly stands out for good or bad?

A friend also advised to look at the Cube Aim Disc http://www.jejamescycles.co.uk/cube-aim-disc-mountain-bike-grey-blue--id65901.html and consider replacing the suspension fork with rockshox or similar however that'd push the overall price of that bike to more than the rest of the bikes and I'm not sure how good the rest of the bike is to just upgrade one component. Thanks for any help.