I don't think DS9 Season 6 is bad, but I think it's a little overrated. As for ENT season 2, it was the weakest season but there were some great episodes here. We got Carbon Creek, the Minefield/Dead Stop arc, and we got more Shran in Cease Fire, which carried on the arc of the Andorian/Vulcan relations. Also, this episode gave us First Flight, which has become a favorite of mine, just because the series was a prequel and I Think we needed more episodes like that.
I actually prefer season 1 to season 2. I give season 1 more credit because I first watched it with the knowledge that it wasn't going to be amazing. Much like the first season of TNG, DS9 and VOY. I thought that season 2 would increase in quality and I felt that it didn't. I also felt like the show was treading water. There were some bright spots but the vast majority of the season was forgettable. That being said, I really believe that ENT hit its stride during season 3 and 4.
I like Season one of Enterrpise better than season 2 the shows were hit and miss. They were treading water the ratings were falling off the fans were unhappy with the storylines in the shows and the studio told them Rick Berman a nd Brannon Braga need to shake things on the series up so they came up with the Xindi storyline which was my favorite season of the series.