Well, then I guess I've got another unpopular video game opinion for you: I think Super Mario Bros. 2 Japan is much better than Super Mario World. Or does that not count as 'classic Mario'? I've only played the GBA version of Super Mario World, though.
It depends on what you like: the Super Mario Bros. triology, or the modernisations (like the introduction of Yoshi) that Super Mario World was praised for. I think SMW is one of the best Mario games.