My first introduction to the Apes films was a Saturday Morning double bill at the local cinema of ESCAPE and then PLANET OF THE APES, in that order.you could theoretically start viewing with any random film in the series
I was able to make sense of it, sort of, and the fact that ESCAPE had flashback clips from the first film when Zira is drugged helped a bit.
Regardless of any confusion though, I was hooked from then on, but BENEATH is kind of my favourite, simply because of the audacity and bleak brutality of that ending - and coz the mutants have got such a macabre vibe to them.
But I love all the old five films. The newer attempts have not won my heart so much, despite any technical advances.