Mine is probably a toss up between Banham and a day spent in South Wales.
Banham - this was a decent zoo, the first visit I've had there in many years, and it was hosting the IZES meet-up so was good to see so many familiar faces (some I've not seen since 2019) and to meet some new ones.
South Wales - this was a double-up of new collections that were very different in scope. Morning was Welsh Owl Garden which has some pretty nice bird species including Sandhill Crane, various hornbills, and (obviously) a collection of owls, but things get rather interesting when it comes to mammals. All the mammal species are small but when they don't include Meerkats but do have Eurasian Otter, Banded Mongoose, Kinkajou, and African Striped Weasel(!) then you know it's a little special... No outstanding exhibitry but just a rather nicely done place set in some lovely woodland in the grounds of a castle.
This was followed by an afternoon at Folly Farm, and yeah, this place caught me by surprise! One of the best lion exhibits I've ever seen, one of the best Black Rhino exhibits I've ever seen, and one of the best penguin exhibits I've ever seen (including Macaroni alongside the Humboldt's) really set this place apart. There's no bad enclosures, the collection is interesting, and the zoo is separate to the farm and amusement park, with only the tropical house being an exception.