Re:better to rest and get more reps or less rest and more reps
I think things like this are really overthinking the issue, and it all depends on your aims.
If you are just cranking out pull ups as part of an overall back routine (a great exercise) then just mix it up a bit.
If your aims are power and you're wanting to go with weighted pull ups / chins, then you need to be looking at the rep range to suit that (5x5, 3x8) with enough rest to get to your required rep/set range.
If you're wanting to improve your endurance with bodyweight only then go for big reps, then rest till you have recovered and go again, repeating till failure or near failure.
... and everything inbetween.
With regards building muscle, I'd go with the mix it up advice. Some sessions do weighted pull ups early and go for 3 x 8, whereas some sessions go for bodyweight and crank out the reps, or alternate it month on month, and use rows, pull downs, deads, pullovers etc in rotation with them.