Personally it's the production and entertainment value that makes a music video since the budget doesn't always matter since there's many low budget videos that are great like Tone Loc "Wild Thing" or  The Go Go's "Our Lips Are Sealed" and not all big budget videos are good (ie MC Hammer "2 Legit 2 Quit").

The song doesn't really have to matter since "Thriller" (MJ), and "Sledgehammer" (Peter Gabriel) aren't the artists' greatest and some songs.  Also there's some music videos I like better than the song like Twisted Sister's "We're Not Gonna Take It", which is one of the funniest clips, but the song itself is a bit corny.  Heck, I like to watch "Rico Suave" (Gerardo) for the female dancers wearing spandex... (the camp value... BTW not saying it's a great video, It's average for it's time)  :D

As for the visuals, it's like a time capsule of a certain point of time of when the video was made from the fashion, choreography, and special effects. Also music videos that are creative like using animation, spoofing pop culture, political/social statement and/or any creative idea.

Actually hard to explain, but pretty self explanatory...

I went with artist, song and entertainment value.