Even though my sig and ave are of Solid Snake, this is still a hard decision. I played through all of Snake's and Sam's adventures and even though they're both stealth, they are quite different.

Splinter Cell takes the realistic approach to things. Not a big surprise since Tom Clancy is involved with the series. Whiled MGS goes for a more fantasy kind of approach, though that's what gives MGS that great storyline and memorable characters.

If I absolutely had to choose one series, MGS would be it. Though Sam is a great character and Michael Ironside really gives him a great personality. The MGS characters and story make this series stand above not just games in the genre but most games period.