I would go for Intel Core i5, since for this price you could not get i7. There are more versions for it, the quad-core for lowest price is in my country for 200€, what is around £140. I have bought i5 3570K 3 years ago and it has still enough power for gaming (BF4, GTA V, Project Cars etc.). In my humple opinion, i5 is the best CPU what you can get from your budget.