would you help me to understand what is better to use for the 3d games Blender or Blitz?
Both are pretty terrible. I would try Unity or Unreal UDK.
Blitz is terrible, don't use it. I'd say Blender no doubt. I still haven't really got into game creation in Blender, but I've seen some very nice high quality games made in it, and some are really nice. here's
a good video that has some great examples.
If you wanna learn the Game Engine, or Blender in general BlenderArtists
is probably your best resource, people there as well as here are very helpful.
Train Insane or Remain The Same
There's No Room In A Warriors Heart For Self Doubt
Yes, I have seen some good uses of the game engine.