I usually look for the story. If the story is very good with solid plot, then I wouldn't ask for more. Then I would look for the animation, characters, duration and such. If they are good, then it's almost perfect.
Then I would compare the music, songs and good moments.
What about you guys?
How do you compare two anime?
I find it much more reasonable if they're the same or similar genre. I think it's a bit silly to compare DBZ and Haruhi because there's almost nothing similar between the two.
DBZ is about a bunch of super powered people fighting each other. Haruhi is a school comedy about a guy who finds out the eccentric titular character is God.