Ok, so i created a new account (pure) and i subscribed membership. I am currently 30 att and 24 str and 1 def. Could you tell me where should i train? Or rock crabs could do just fine?

Flesh crawlers, experiments, rock crabs, slayer

I would go train up your defense on some very easy monsters, such as goblins,cows or the barbarians in their hall, for a few levels so that you don't go through a ton of food when training. Then head to the stronghold of security and find the monsters you like to kill. Flesh eaters are great for experience, but I'd recommend finding the monsters that you like to kill the best. You'll probably gain more experience in the long run if you are enjoying the monsters you slay.