I personally love the zoo and think it is fantastic...
I agree with you; Bristol Zoo is definitely amongst my very favourite UK zoos although I do miss some of the animals that were previously kept.
As others have mentioned, the collection is much reduced when compared to days gone by. I especially recall that, during the 1980s, the Nocturnal House displayed some choice species such as Philippine tarsier and pacarana.
Given the relatively small size of the site, I think that removing most of the large mammals was sensible but, personally, I miss the okapi enormously (although Bristol, of course, still keep okapi at Wild Place).
Even after all these years, whenever I see the pygmy hippo accommodation, I always wonder how black rhinos were kept (and achieved first successful UK breeding) in such a small building.
My favourite animal at Bristol was "Charlie" the Siberut macaque; the zoo didn't know exactly what species this monkey was and it was only identified after its death. I think that the Bristol animal is one of only two specimens known, the other being a monkey that lived at London Zoo in the 1930s.
Just a few other miscellaneous animals that I especially remember from past visits to Bristol, when the collection was much larger:
polar bear, sun bear, pure bred Bengal tiger, giraffe, plains zebra, African elephant ("Christina"), Asiatic elephant ("Wendy"), Arabian gazelle, orang-utan, chimpanzee, Allen's swamp monkey....