I still think it's the weakest of all the series
What arguments support this proposition?
To begin with, the characters are comparatively shallow when compared to the ones in previous series (including Voyager.) The actors also don't do as good a job, in comparison. Plotlines are often weak and a bit too showy, there's less insight into human nature and very simply ... I like the others best, with their own faults and idyosincracies.
But I don't want to get in an ENTvsThe Others argument . We all have our tastes, and they're all different, luckily. ENT is an excellent TV series, but in my opinion when compared to TOS, TNG, DS9 in part and VOY sometimes, it's not as good.
I should add that I'm not a conservative trekker, I welcomed Enterprise as potentially better than DS9 and VOY, but it disappointed me. Again: tastes, not much to do about it.
PS. I just read you have never watched other series. Watch TNG 2X09 "The Measure of a Man", TOS 1X28 "The City on the Edge of Forever" or TOS 1X14 "Balance of Terror". You'll probably see what I mean with plotlines, characters' depth, actors, humanity and so forth.