There isn't really a right or wrong answer as far as what morph to add goes. Anything you like is going to be a good choice, especially since there aren't a lot of bad combinations you can get from a bumble bee. I wouldn't pair anything with spider, woma, or champagne because of high fatality risks, but otherwise all combinations will come out beautiful. I have a bumblebee and the first male I plan to put to her is my calico pastel, because I particularly like those possible outcomes (come on calico killer bee!) but I'll probably also put her with my cinnapin and maybe something with lesser or mojave in it down the line (only have a lesser bee now and I'd prefer not to take that gamble).
But seriously, anything without a wobble goes well with a bumble bee!