Well the title of the thread is pretty self-explanitary. Which series of games do you prefer and why? I am definitely more of a Mario fan. I know this will sound lame, but I like Mario games more because they are easier. I have yet to complete a Zelda game.

Zelda.... I blame Ocarina of time....

I like mario more
mario games are more fun, easier, innovating, and good for all ages
and grew up with playing mario
I like zelda too but sometimes it gets a little hard at some spots

I like zelda more. (There was an elimination thread about this, zelda and mario were the final two, and then mario got murdered.) In other words... from what I can tell more people seem to like zelda on this site, however, you could get different results.

Zelda is my favorite series, then comes Mario.

Zelda... OoT

Zelda. I blame Link's Awakening

However if you were to consider Yoshi's Island as a Mario game, I migth have some second thougths, but Zelda would still come out on top 

I started off on Mario when i was like little, first game i ever got with my nes at like 5. But i do have to say, Zelda is way more my favorite franchise. If i buy a Wii, itll be for Zelda, i have really no true interest in Mario. Hell, thats why I still have a N64, just so i can play the 2 zeldas there, haha.

Zelda hands down, Mario is great and all. But when i first played OoT i can't describe my feeling

I gotta give it to Zelda, by a small margin. It's just so incredible.