Aside from the obvious Torres , Villa , Rooney , Drogba etc etc , I think the best one's considering their value and availability are -
Leigh Griffiths , can be bought for as less as £250K and the start and will guarantee goals in the Championship.
Garra Dembele - Again , can be bought for less than £1M and is a monster in the Championship , and very good for most Prem teams.