Currently it's still FFXIII in the PS3, and there is many a comment banded about the interweb about the likeability (or annoyance) of the characters... with the consensus being that...
Snow can't stop with the word Hero which makes him sound arrogant
Lighting is as emotional as a block of cheese
Hope is a whiney emo kid
Vanille is like dragging your fingers done a chalkboard made of sugar
It got me thinking about the longevity of any character in any game. Final Fantasy is well known for not having "sequals" with each new incarnation placing you in a new setting. This hasn't however stopped the cast of FFVII being some of the best known characters in gaming history with only one adventure together. So much so that a CGI film brings them back together to round off the story, and several spin offs were made years after its success.
Mario and Sonic on the other hand... starting way back when I still had an awful 1980's child haircut... have had more outings than all the Ashes series in that same time. The games were all okay back then, as there wasn't such a huge expectation for epic scenery and challenging boss fights... hell there wasn't really a story until Sonic 3 came along and had side scrolling equivelants to cut scenes.
These characters have long term staying power but it sems that they don't feel the need anymore to work for that status. Lara Croft is not far behind - I am sure the only reason that she has stayed so long is that the game playing populus a predominantly men. Uncharted may be "better" according to some reviews but men have got used to pushing Lara's buttons.
The latest characters are joining a Marathon in its closing stages... Sackboy form LittleBigPlanet is endearing but will he be remembered in 2 decades time as Sonic has been? Will Sonic still be with us then or will his big red running shoes have been hung up? Now that games are getting BAFTA awards it has made the expereince of gaming more than just a button bash or a mouse click. We are invited to become emotionally invested in storylines, characters plights, scenery and more.
The characters in FFXIII may seem annoying to some but to me they don't need to be long term companions. We probably won't see them again, and once I am done with the 60+ hours of questing I probably wont go for a second playthrough. So long as my attention is held throughout the game it's all fine with me.
51 minutes ago