I've read articles that say a 3 wire is better. A one wire is an easier hookup. Alos you have lots of car guys using both and having no problems. I personally had a 3 wire on my pro street car for 9 yrs with never a problem.
It's basically whatever you decide you want or already have.
The 3 wire has 2 tabs sticking up on the top left of the alternator as I remember.