Dumping someone or getting dumped?
Getting dumped on has my vote.
But yes, getting serious, I'd have to say (while it depends on the circumstances) that getting dumped would be more harsh. Usually if you are going to break up with someone, you already have a reason to want to be separated from that person...if you are the "dumpee," then it could blindside you and really hit you hard. "Love is about control" as the mighty SYL have said, and I guess this situation is no exception.