The fourth Planet of the Apes movie, the one with Caesar leading the Ape revolution, is my favorite of the sequels. It's the best pick if they're going to remake any besides the original.
Yup, Conquest is a gem. If they had only had the same level of makeup quality of the original, it would have been truly awesome.
I watched it again the other day, and I am just amazed at what they did with essentially a microbudget. An ultramodernist landscape has never been as convincingly portrayed in film. I also can't think of another film where the use of color in the production design is as effective, unless it's A New Hope. And if the scenes of the ape revolution had just a few more extras or maybe if someone could travel back in time and give them a little CGI, they'd be the Cecil B. Demille of B movie sci-fi.