How could one chose their favorite child
I love all handguns. All other firearms as well.
but to answer your question I'd say
1. collecting = both, especially for me, my collection has a long way to go!
2. hunting = revolvers
3. defense = both/either, whatever you shoot best, for me its my .357 mag revolver but I usually depend on my 9mm auto because I shoot it well too, and I think follow up shots and capacity are important, as well as speedy reloading. Also I think 9mm is sufficient for defense (might switch to +p ammo after I practice with some) and the .357 has a little much kick and slower follow up shots (I prefer to shoot in single action, unless the BG was right up close.) and capacity and reload speed. If someone broke in now I would grab my 9mm w/ extra mag and my .357 mag in a clip on holster for backup.
4. Recreation = both. I wouldn't go to the range/ gravel pit without both!
For me its basically a tie. I do lean towards autos for defense, providing you have quality ammunition and keep it well maintained, and have plenty of practice with it. But its a tough decision for me. I have seen too many autos jam, but mostly due to poor ammo/ gun not being clean, and have yet to see any revolver malfunction. Overall revolvers and autos will always both be in my collection.