I know this sounds kinda cheesy but it's very important to keep edits your own. As in, your creative/artistic vision, not somebody elses.
For me personally, I have a very clean editing style, I don't like over the top edits or color correction and I just try to keep the frag as understandable as possible, and I put more of my vision into the song sync, clip cutting and transitions, not to say I wouldn't deviate from this; i've done it plenty of times for PotD but it depends on the frag, mood of the song, smooth, etc... Usually I just let the frag speak for itself. As a viewer I know how to appreciate more flashy edits tho as I know how much work they take.
I would say the single most underrated thing a lot of people editing videos disregard is clip cutting. It's the one thing that can transform the entire pace of a fragmovie and keep it super tight if done right. I've seen it so many times, even on major tf2 channels, clips ending too long after the frag, or starting too early into the frag and it really bothers me.
If it's a fragmovie (not a fragclip) we're talking about for me the biggest factor in enjoyment is the song. I usually plan my entire workflow (after recording) based on the song. Because a good song (or a song used in the right way) will link the frags smoothly and keep a very nice vibe to a movie. Syncing the song with the frags is a must (or should be) even if it's just major anchor points in the song, even if the frags are already good, the song can complement them even more and take it to an other level. Last but not least a good song choice is what makes a fragmovie memorable, you will be able to remember it in your head for ages, that feeling is even better if you don't know the artist or song and you get hooked to it because of that fragmovie. I still can remember watching Pop Culture by Cla for the first time, it was the first time I heard madeon as well, and watching such a work of art in front of me was a fantastic experience, both frags, editing and music.