I currently oficiate volleyball and softball. Had to give up basketball due to leg injuries that no longer respond well to the pounding on the hard court.
From my experience, basketball is the most difficult sport to officiate. It is a series of snap judgements while having to constantly re-position yourself to follow the action. With two officials, it is difficult, but doable to watch ten players, with three officials, that job becomes easier.
It took me about three - four years of doing volleyball for the light to come on. The rules are not quite as complex as basketball or softball, but there are several things that an official needs to know and be aware of. There is almost no physical component to officiating
VB, but it is very mentally taxing if you want to do it right.
I've been thinking about becoming a track starter...where else does your job consist of pointing a gun in the air and firing blanks??