I mine whatever algorithm is paying more when exchanged to bitcoin. At this time there's only 2 algos that work for me. I choose pools where I can auto-exchange to bitcoins.

No idea about the different kind of 1080s. I think the difference might not be that huge. It also depends on what software you use. You will need to do some testing and tweaking.

On some pools you can see statistics from other users, like these:

http://yiimp.ccminer.org/bench?chip=387
http://yiimp.ccminer.org/bench?algo=skein
http://yiimp.ccminer.org/bench?algo=nist5
http://yiimp.ccminer.org/bench?algo=quark
http://yiimp.ccminer.org/bench?algo=x17
http://yiimp.ccminer.org/bench?algo=x11
etc etc

You will need to do some homework. PM me if you need more help.