Opposites attract?

My parents had a long but relatively happy marriage. My mom always told me she loved my dad because he was so different and interesting but the same things she found attractive to begin with became the cause of stress in her life later on. They had barely anything in common and never did anything together because they interests were so different. Sure they loved each other but it seemed like they stayed together just because it was easier than divorcing which is depressing to me personally as a relationship without some spark left and just habit is something I really want to avoid - I'm not talking about post honeymoon phase but reaching a point where there's nothing interesting left.

Because of their relationship I actively avoid getting into any relationships with someone too different but don't know if I'm being unreasonable because of my parent's relationship or if it's just a personal preference.

Any experiences?