I'm confused with some of the above responses. The wiki section says Collins is forward-facing (only), but I see comments on Collins rear-facing seats.
I have a flight coming up on a 772. I don't see any rear-facing seats on the AA seat map, so I assume it's a Collins layout. I'm currently in 1L because, on United, the bulkhead seats maintain good privacy and have much larger footwells. It sounds like that isn't the case here, though. Should I move to 2L or 5A? Or the rear mini-cabin is entirely empty, too.
For 772 flights the seatmaps at aa.com will display the all forward facing config by default, however the actual config is not known until a day or two before the flight. The seatmap will update at that time to show the arrows if your plane is scheduled to be a forward/backward config, and even then it can still change further on day of departure.
Below is the detailed thread on how to tell which 772 you'll get:
Aircraft guide: Which 777-200ER / 772 / 777? (2019 on)
Also on AA's 772's the bulkhead seats are exactly the same as the others.
As to where to sit, it's really personal preference, most of us pick a seat that will work regardless of config, i.e. if you want to guarantee a forward facing seat pick one that's forward facing on both, etc.