I ended up fighting Asgore twice before I was told I missed something important, namely hanging out with Papyrus and the subsequent sequence of events (Undyne, True Lab, etc). I figured out that Alphys created Flowey before the game implied it. I never really liked Alphys (especially after seeing what happens between her and Undyne... ugh), so that just makes me like her even less.
The fight against Asriel was cool, but I felt maybe he was just a tad bit OP. I mean I know you can't really die, but it still seemed a bit much to me. I still hate Flowey though. Don't get me wrong, I don't hate Asriel; Flowey and Asriel are not the same, despite what the game might make you think.
I do like the ending however. Nobody dies and everyone's happy. For reference, I stayed with Toriel. I may load my save back up someday and see if I can simply choose the other option just out of curiosity, but I'm not sure if the game will let me.
To be frank, I kinda like the neutral run a bit better than pacifist. Not because you can kill people, but because I enjoy the fight against Asgore more than the fight against Asriel. Maybe it's just the music, but it just feels more epic to me. It fills me with DETERMINATION, whereas the Asriel fight fills me with feels. I don't count Flowey as the final boss of neutral because he's a massive prick and you don't fight him again on a second playthrough (at least, I haven't fought him again).
The extra stuff for the pacifist ending felt more like padding than real content to me honestly (though I have to admit, hanging out at Undyne's house was pretty funny). True Lab was kind of a pain and just plain creepy (another reason I've grown to dislike Alphys), and the final boss gauntlet also seemed a bit drawn out and longer than it really needed to be. That might just be me though, it's actually been over a week since I completed the pacifist run so I may be remembering wrong.
Basically, to sum up, my favorite way to play the game is pacifist but with the neutral ending, sans the Omega Flowey fight.