Of my two bettas - Muriel and Ulmo.
Definitely Ulmo. He's got such personality. He is SO curious, and gets bored easily so he does have a tail biting problem. But he's super-interactive. I had (literally HAD) to get shrimp so he had something to do when I'm not there to play with him outside the tank. He chases things around the tank, he rolls his Marimo ball by suckin' on it. He flares at things, is so super-curious about EVERYTHING. He's very active, too. Ulmo likes his little bubble-maker and "eats" the bubbles when they reach the top. He'll swim through the stream and float there, almost like he likes the feelings of the bubbles on his body. He doesn't blow bubble nests, but is just perfect.