Which is more fun and which is better made?

Seriously..?

Little big planet, wouldn't even think twice.

I have doubts you've ever used Garry's Mod.  Poopyhead..

LBP would be more fun cause you don't have to deal with complex stuff like in Garry's Mod but you can make much cooler and varied things in GM. Both of those lose though to real editos like UE or the actual Source editor since with those you can make up brand new games, but that's too difficult for the lay people.

and i doubt you have ever played Little big planet.

Naturally he didn't, that why he is asking which is better. *cough* idiot *cough*. As for the answer Vlad is right, LBP is more "fun" but is much more limited in term of what you can do, doesn't necessarily mean bad though, I encountered a really good game made with RPG Maker once.

Don't forget LBP multiplayer goodness.

Between the superb story mode and easy to use level editor I'd have to vote for LittleBigPlanet.