Well, before I give you all the verdict, I have a few things to say about those two.

If you are a true gamer than you know of the ever popular and growing worlds of Super Mario bros., and Sonic the Hedgehog. But, do you know which is a better series?
The origin of Mario started with a 1981 game entitled, Donkey Kong. Donkey Kong was the first big hit Nintendo made, and if you play it, the simple, run run run jump run jump system, is addictive. After that succses, Nintendo wen't on to making, Mario bros. in 1983. Mario bros. was the birth of Luigi and many of the well known enemies. All it was, was that enemies would come shooting out of pipes, and as Mario or Luigi, you would bump them on the head through the floor. Although not as addicting as Donkey Kong, it was a succsess, and 3 tears later, Super Mario bros. was born. The rest is history.

Mario continued to be the video game industrys poster boy, but not without fierce competition. Many spin off Mario games were made, but none of them spun off as well as Sonic the Hedgehog. Sonic was eant to over power Mario, but all he did was mearly rival him, the classic run run run run jump run jump format was featured in this game as well, but when things got rollin', they really got rollin'. As the name Sonic implies, he is a fast paced mamel, of the porcupine-ish family, who instead of being a human fighting animals (as in that of the Super Mario sereis,) he is an animal fighting humans, well a human, doctor Robotnik AKA eggman. These two games both have a quirky or odd feeling to them, but that does not change much, they were still succseful, now lets look into the year 1999.

Two new systems were made, the Nintendo 64, and the Sega Dreamcast. Both creating a new type of gaming experience for both mascots. Super Mario 64, again the run jump otherwise known as a platform game, came back yet again, but not without a twist, the new game was all 3D, and featured a new way to fight Bowser, although it was dorky, you grabbed him by the tail and swung him around, hoping he would hit a bomb when you released him.

Sonic Adventure, an all new kind of sonic game, mixed the run jump platform, with sonics old style creating a fun new expeirence. Introducing about5 new characters it was by far one of the best games of the Sonic sereis.

So now we know all this stuff about the two and the sorts of things they have done, Sonic recently released a new game, Sonic rush adventure, and Mario will have his all new game Super Mario galaxy, will be realeased this November, also the two will be meeting each other in a face off not only in Mario and Sonic at the Olympic games, but Sonic is making an appearence in Super Smash bros. Brawl.

And now that we all have this knowledge of the past, and future, who's better? It's simple, neither. We all love them both and they're both great characters, so they both are the greatest of all times.