3 speed AM is meant to be good, although my (coincidentally 1947) example has seized fast, probably due to a pawl spring disaster, and needs sending off to be fixed, so they aren't fool proof. I think AW and maybe FW's are solid and can go on for ever as long as aforementioned pawls don't wear (maybe an AM as a club gear would see heavier use than an AW off a utilitarian bike such as an old Raleigh sit up and beg?) AC's are fiddly and on some models are very very close ratios. ASC's are obviously a different story as fixed but mine is fun, WHEN I can get it set right. TF's are Hilary Stone's favourite Sturmey but are really a 30s gear.
Sheldon Brown's big table of Sturmey models is very useful. Find it here: https://www.sheldonbrown.com/cribsheet_s-a-hubs.html#tbfc
SO, I'd say an AW is the safest bet but if you fancy something more exotic try and get one with as little use as possible, the problem being there is No real way of knowing the amount of use one has had as you can't see any wear externally really at all by the very nature of an internal hub gear. I think they are a bit of a fiddly nightmare to service but instructions and excellent exploded diagrams can be readily found on the internet.-Check 'Hadlands Blog ' and Sheldon Brown. I have toyed with the idea of fixing my stuck AM my self, but that doesn't mean it's a good idea and I should probably send it off to be fixed by a pro!) IF you are a more patient and methodical person than than me with a keener engineering mind than perhaps give it a go if you can find a cheap one. -the issue being here you really need to build it into a wheel and test ride it in anger to uncover any lurking problems, by which time it is rather disheartening to have to take it apart and try to salvage it!
Don't be put off though, they have a lovely simplicity all of there own when working, and you learn to love the gentle tick they make as you ride along.....