Top 5 sci-fi alien races/empires I'd love to be enslaved by
1) Ur-Quan (Star Control series)
They either put you on your homeworld and trap you there under an impenetrable slave shield or make you a battle thrall. I think that's some fair treatment when they could just kill ya.
Plus they're badass. It'd be an honor for me to fight in their campaign.

2) Borg
They ain't pretty. And they ain't smart. I mean they'd let the damn crew of the Enterprise beam aboard w/ weapons when you know those slick assholes were not up to anything agreeing w/ their agenda of assimilating all.
But I bet it'd be damn awesome to be part of a grand collective like that. Probably some sort of major mind fuck. Plus maybe 7 of 9's regen thingy pod will be next to mine
3)Minbari Federation (Babylon 5)
A society of warriors, priests, and builders. Granted I'm not enough of a tank for the warrior caste, I probably would find a calling in the Third Fane of Chu'Domo and begin the search of enlightenment and reason. Not to mention kick ass. Their priests are basically warrior monks.
And it'd be sweet to tool around the galaxy in one of these badboys

4) Old Empire (Dune)
Thinking machines are abolished, forcing humans to achieve their highest physical and mental capabilities to replace tasks previously done by machines.
Though, this probably didn't bode well for the average dude, probably making him a slave or cannon fodder.
Still it'd be nice to have some spice melange. Mmmmmm melange.
5)Galactic Republic.
I don't know much about the actual fiction here. But it seems like shit was right for a long ass time. 'nuff said