regarding 1P bomberman, the '94 is maybe the better one, since it offers more complex stages and secrets etc. but i never really went into the fun of playing BM alone.
for the multi-P BM, the '93 ist the ultimate one. here some reasons for:
1. same driving and best ever made BGM in any BMs, taken over from part 1.
2. very balanced with the items (not to much, not to less). the biggest improvement from the 1st BM was the bomb-kicker. this is the most tactical and important item, right after the flame-power.
3. not playing around with some unnecessary falderal nonsense > be simple but efficient is one of BMs most important attributes.
4. and last but not least, its much better and more cute "pause"-picture.