But with EDs, most of the time stills or minor animations are all you get. Hell, all that happens when Song for Friends, which is winning this poll right now, plays is scrolling credits. Anything beyond that is really just a bonus.
In terms of both OPs and EDs, of course the best song may not have the best video/art to go with it, and the one with the best video/art might not have the best song. So if all you really care about in an OP/ED is the music, then you’ll choose the one with the best song. If you’re some weird psycho who doesnt care about music, then you’ll choose the one with the best video/art.
But I at least consider both when Im deciding this, and whichever OP/ED I end up choosing as being “the best” might not be the one that I think has the best song or the one that I think has the best video/art. It’ll be the one that I think uses the best combination of both to either open or end the route, episode, story, etc.