Well, PE is a useless metric for MLPs so that shouldn't influence you.
I don't really follow CLMT closely, and ACMP is in the category of MLPs (NG processing) which I invest most in. So my personal choice of which of the two to own would always be ACMP..
However, ACMP is definitely getting to the low end of plausible yields, so not sure that now is the time to be buying. I'd suggest put it on your list to buy in a market 'event'.
Don't really follow CLMT closely enough to suggest whether it's a buy right now or not.