Rats.
Very intelligent, also they are large enough that you can pet them, carry them around ect. without the worry of hurting them.
Even raised with attention and people, I found that mice were more skittish, one was very loving, out of 20, but even she only came when SHE wanted to.
Hamsters are cool little guys, but I would get a baby to raise, or else they may be aggressive/shy.
I stick by rats, they are very personable, and if raised right very nice pets. I wish I could own one, but the rest of the family thinks they're 'nasty', which is not true either, they may smell if you have a male and don't clean the cage every day, but they are rather clean.