i was going to post saying giant gourami but then thought that for me "friendly/loyal/tame" would mean being able to put my hand in the tank. I don't dare do that with Juju.
But she is the most responsive, intellegent, interactive and attentive fish i think i have ever seen.
We have got her jumping a foot out of water on cue and she rings a bell. The kids play "tag" with her, and she knows when there is someone at the front door.
Otherwise my close second vote will go to bettas. at least you can pat them and teach tricks and they are very responsive and interactive too