Enterprise was great when it was allowed to be the prequel it was meant to be. The actors were great. Set and prop design was on point. There were interesting ideas to explore during that time like the Vulcan-Andorian Cold War and the increasing destabilization cause by Romulus.
Cut the Temporal Cold War and the Xindi and Enterprise could have gone on for seven seasons and we might have seen the Earth-Romulus War.
I actually liked the Temporal Cold War stuff and the Xindi arc, but that fourth season was so damn good. I wish we'd gotten at least a couple more seasons like that.