I think that Homer is mean to Flanders because he is jealous of him but deep down want's to be more like him. Perticulary in the Diatribe of a Mad Housewife. When Marge wrote that novel that potrayed Homer as a jerk and Flanders as the knight in shining armor. It seemed like he was going to push Flanders down the cliff. Homer gets on his knees and says can you help me be more like you. As Lou once said it's eaiser to be cruel than say how you really feel (Last of the Red Hot Mamas)
And on a humorous note. I found it funny when Homer made that dating tape for him when he videotaped him in the shower.
A couple of my favorite anti-Flanders quotes
Kent Brockman: Remeraber millionaire C. Montgomery Burns? The man who blocked out our sun, ran over a local boy, and stole Chrismas from 1981 to 1985? Well, guess who's flat broke, and picking up trash for a living?
Homer: Please be Flanders, Please be Flanders.
Homer: Who spread garbage all on Flanders lawn before I got a chance too