Out of all the Star Trek series, I generally keep returning to Enterprise for more. I'd like to think that's down to something deeper than having seen the others too often.
I love the characters, while being the less than moral humans he would've created, they do in fact hold true to the Roddenberry ideal - that of ordinary people in extraordinary circumstances. Archer, interested me from the outset (being familar with Scott Bakula's other work) his Captain out there alone with no support, no rulebook or role models to learn from their mistakes. His 'quid pro quo' relationship with Shran, with whom he forms a bond, both skeptics of the Vulcan's agenda and yet building bridges that will ultimately lead to the Federation's birth. Trip, likeable Southern Engineer who's deep friendship with his Captain, manages to survive his occassional bouts of insubordination. T'Pol, initially an observer from a Vulcan government concerned about the impact of humankind's deep exploration. Growing more accustomed to the crew and their perspective, seeing how her race aren't right. Her relationship with Trip, which manages to rise above its somewhat exploitive origins and her struggle to maintain control over her emotions. At this point, I should also make it clear I loved what Enterprise did with the Vulcans and how they are everybit the race seen all the way back to the Original Series. I could continue to outline traits of the various other regulars, who are anything but cyphers in my opinion. Under developed in comparision to the big three for sure but I feel that was changing... even Mayweather got some action towards the end.
I love the technology - grapplers instead of tractor beams, phase pistols and EM rifles, airlocks and shuttlepod deployed from bomb bay doors underneath. When you're at a disadvantage, you have nothing but your wits to rely on and this show was about as far from Voyager's technobabble saves the day approach as it was possible for Trek to realistically get.
I love the setting - an earlier century than even the Original. I still believe this is the show with the most potential left unexplored. 2 reasonably good seasons, 2 excellent ones which kept me watching and yet still barely scratched the surface.