I personally voted for DS9. (I know, surprise surprise.) This one had me on the verge of tears... particularly in the show's last 10 minutes when each character got a brief montage of memorable moments from the series. It really conveyed the sense that while most of these characters were still alive and well, that we'd never see them again and that the show was over. Powerful stuff.
In contrast, the series finale for ENT was a hot mess. I liked the show a lot (second favorite after DS9) and I thought the show deserved a better send off.