I donīt think, Archerīs line was that
bad. Surely, neither Kirk nor Picard would have said that, but Archer is a different character and from a different time. The line isnīt unlike his character and we donīt know if he would actually go through with his threat - after all, he said it in a flash of anger, when Porthosī life was in danger.
For me it is difficult to choose one "worst line", since there are so many silly, stupid and redundant lines being said over the decades. From the TNG movies alone there could be several examples. But for the sheer implications, I think by far the worst line is Spock in Patterns of Force, saying to Kirk as he puts on a Nazi uniform (an SS uniform, no less):
"You should make a very convincing Nazi"
Attesting his own Captain, that heīd be convincing as a Nazi
is beyond comprehension to me. Next to that, all the silly jokes or badly written bits and pieces pale by comparison, IMHO.