I know you've had a lot of HW100 recommendations already, but i'll offer mine too.
I've had my 100 for just over a year now, and its astoundingly good. With good optics and the right pellet, you really can put pellets through the same hole at 35 yards.
My mate has a BSA Scorpion T-10 which is also a great piece of kit, its lightweight and feels good in your hands, but the bolt action is a lot more clumsy than the HW100's side lever, and the magazine is far from ideal. The HW100's mag on the other hand is flawless.
Check out the AA S510 though. I haven't held one in my hands, but if