Broly vs Doomsday: charting into manga/anime territory (manga is technically comics), it would be awesome to see these OP characters tearing it up as they face each other on a neutral plane of existence in which these two can go all out. Ultimately I think Broly would win but then again, Doomsday has been through a lot and has those extendable spikes.
Lex Luthor vs Norman Osborn (Green Goblin): both of these businessmen have a wide range of technology, great intellect, and have been known to go a little nuts at times (mostly Norman obviously). This would seem a bit of a close call but if there was a deciding winner, I'd say Norman. While Gobby has insanity on his side, Luthor at times has let his ego get the best of him.