This is a tough one, coz it really depends on what you wanna produce in the future. We can easily suggest certain morph on your list, but each of them produces different lookin combos. Like do you wanna produce bees or do you wanna produce non-bee combos w/ your pastel? So let me provide you a short list that will show you the possible outcome when bred any of those males to your pastel.

Cinnamon x pastel = pewter
Spider x pastel = bumblebee
Black pastel x pastel = black pewter
Fire x pastel = firefly
Lesser x pastel = lesser pastel
Butter x pastel = butter pastel
Enchi x pastel = enchi pastel
Mojave x pastel = pastave

Now which of those do you want most?