I don't like either kind very much. Pull-ups are only diapers to me by the broadest definition. AIO diapers tend to be more trouble than they're worth in my experience, needing plastic pants, taking a long time to dry when laundering, etc. The bit about plastic pants isn't so bad since I don't generally like the feeling of an AIO cover but it grates when I think of the function of the diaper contrasted against the name "All-In-One".
I prefer thinner diapers for wearing out and about. I don't need to go often (8+ hours is normal), so capacity isn't important until I need to change. Unless I'm 24/7, I wouldn't generally put on a diaper just to do something out in the world for a few hours.
"A couple hours" and "a whole day" to me are two very different things. If I'm out a whole day, I'll wear at least my typical day diaper (currently an Abena M3) or better and have my diaper bag nearby. For just a couple hours I'd go for a thinner tape-on. I also like the Tranquility ATN's but am intrigued by the Molicare Comfort Super (plastic center, cloth sides). I typically wear pull-ups when exercising or for short periods at home between changes. The AIO's are cute, but am not sure they're very practical. It also depends on how much protection you need.
Abena Abriflex 3 pull-ups last me for hours. Typically good from 7:30 am until well past 1:00 pm most days, with a number of heavy wettings. Of course if you do a BM in them, that is another story because you don't typically want to spend 4 - 5 hours in any dirty diaper. Although an hour or two in a poo'd diaper isn't a terrible thing...
I basically wear Goodnites everywhere I can (only done a couple times to work and never to class), I just love the way they feel and how they feel when flooded. I have Abena M4's, but not the plastic backed I had hoped to get, the more breathable air diapers that I don't like as much.