Transformers, but I'd concede that for Americans it's harder. The UK Transformers comic was fantastic (Megatron and Galvatron teaming up to wipe out the other Transformers, an issue-long fight between Prime and Grimlock, Grimlock's dream where he slices Megatron in half and rips up the rest of the Decepticons, etc. etc.), quite simply, while the US one was slightly rubbish, until they started using the writer and artists from the UK. The first couple of years of toys, where they actually looked like real cars and stuff, and then turned into robots - how can you get better than that? And a tape player with cassettes that all turn into robots? And the Dinobots? Hell, in the UK, the letters page was answered by Soundwave, Grimlock and Blaster.
Question - when we're doing these HARD QUESTIONS, why don't we do them as polls?