Discotek Media are awesome, no questions asked. My only gripe is that they don't usually do dubs of anything. Even Jigen's Gravestone's dub is a gamble at best, and only Discotek themselves know if that'll lead to anything more. Besides, that, though, I've no complaints, and I'd take subbed to nothing. Though a dub is coming into existence, so they may use that. Given that they like Lupin, it wouldn't be a shocking acquisition.
I have no problems with giving Funimation my cash. I rather like them, myself. Their dubs aren't always the best, but even at worst, I usually find their dubs servicable. I don't know what the chances are for them.
Sentai Fimworks I'd also be okay with. Their dubs I hear have been improving, and even their sub-only releases are better than not getting a release at all. I don't think they ever brought over anything Lupin III even when they were ADV Films, but there's always time for that to change, so who knows?
Media Blasters...well, can't say I really like them, especially if what I heard about voice actors not getting paid for the Squid Girl dub is true. But if it has to happen, it'd be preferable to nobody licensing it. But I don't really like them, so I'll only give them cash when I really want a series or film, and they just happen to hold the license for it (like Destroy All Monsters, which I have, and the aforementioned Squid Girl). Unlikely to fall into their hands; please let it not.
Just keep it away from Aniplex USA, they charge more than they should. I might still buy from 'em, but I'm not a fan of their prices. That said, it's highly unlikely to ever get into their hands...but stranger things have happened.