LogFAQs > #975300590

Why not both?

Honestly both are good in different ways, but if we compare the first arcade game from each series, the game that started it all for each franchise... even taking into account the year and tech available at the time...

Metal Slug is the objective winner in that specific contest.

You can find the original arcade Contra in various collections of emulations, I recently played it again on the Contra collection on Switch, and it does not hold up as well as Metal Slug. The controls are stiff and it lacks the balance of the NES port. This is one instance where the home port was better than the arcade. The Famicon version in that collection was even better with additional cut-scenes and more level details.

So now it gets a little more complicated comparing the various sequels and ports from each franchise... but going back to that OG game? Metal Slug.