Plus, no one considers Flashback among Voyager's better episodes.
Actually, I do.
But to answer the thread question, by no means. While I personally prefer TOS, TNG, and DS9, I also find aspects of VOYAGER, and ENTERPRISE enjoyable, like the example I noted above.
I'm in the middle of an ENTERPRISE re-watch right now, and am about halfway through season two. Popular opinion has it that season three is superior to season two. My dislike of the Xindi arc is well known around here, so I won't go into that again, but I find that season two has some of the shows better episodes. For example:
A Night in Sickbay (It doesn't deserve the hate it gets, it's not so bad)
The Crossing (one of the shows more original ideas)
Regeneration (I don't get the fan hate for this one either. For the reasons I like it, listen to Mike Susman's audio commentary. His reasoning more or less agrees with mine.)
That's not a bad run of decent episodes for a show that overall, is not one of my favorite Star Trek series.