I'd vote against navy seals; probably for delta force. My knowledge is limited, such as it is, but it's my opinion.
The reason I'd vote against seals is just from conversations with some marine friends. Bowden (author of black hawk down) describes the "d-boys" as not having any real command structure, which they can do because they're all superb.
The seals--this is my understanding--have the same lack of command structure, but they aren't as superb. So friend [marine] said to captain of the seal team "i'm going to clear the range (squad-based range with popup targets) and I'll tell you when I'm done. when he was coming back, he sees a seal on the range as he comes over a hill. Seal says "dude, I almost shot you" as seal was there before he was supposed to be. Seals spent all their time sunning themselves, he also cites. (though to be fair, this guy also said that seals are probably great in the water).
So if you want to blow up a ship, use the seals. if you want to do something that isn't on water, use delta force/sas.
Don't join any of them, because you might die, and death sucks