I think my favourites would have to be the aforementioned "...Up The Khyber", "...Cleo", "...Spying", "...Cruising" (just love the bit where Dilys Laye says "Her-cu-lees!" about the physical trainer bloke :lol: ) and, best of all, "Carry On Screaming!" - I think Harry H. Corbett is brilliant, even though the role was obviously meant for Sid James.
I like nearly all of them really, although the quality tailed off a bit in the '70s, especially the last few films.