My vote is "Funky Nassau" because I find the beat to be funkier. Nonetheless, "Tighten Up" is no slouch.
Big Stacks from Kakalak
Nassau is "Like a worn out recording of a favourite song" (Piña colada-R) whereas TU is still relatively fresh to me.So, +1 for "Tighten". This, I find hard to believe. At this point I'm more likely to hear "Tighten Up" on the oldies station than "Funky Nassau." That said, I love both equally, but "Tighten Up" if I had to choose.
First time I heard FN I thought they were saying "fuckin asshole"