Reply #14: I'd say it's between Churchill and Attlee..

[Spider Jerusalem]

Churchill was a brilliant and inspired leader in a time of grave crisis, and I give him marks for his early support of a national health service, too (something most tend to forget about him); but his reactionary imperialism probably led to the Suez crisis (which had its roots in his second premiership), and it's hard to find much admiration for his abilities in peacetime.

Attlee gets credit for implementing the NHS, overseeing a smooth transition to independence in India and Burma, rebuilding and restructuring industry post-war.

Both very effective, and given the different challenges each faced as PM difficult to say one was "better" than the other.