Don't know about him...but I actually happen to like both, for different reasons.
If you ask me, it all depenRAB.
I think the TV series is the definitive version of Gurren Lagann. I can't speak about the second movie yet, but the first one is good, just not enough for me to go out of my way to find a DVD release. It's the sort of thing I would prefer to watch on the big screen, if possible, or during a special TV showing.
I'm certainly not against compilation movies, but I also don't need to own everything from any given franchise if there's a superior alternative available. In this case, the original series remains better than the first movie so that's what I'd buy.
However, if both movies were released in one package for an attractive price and with nice extras, maybe I could buy that too.