One wire alternators
pro: Simple. Only need to hook up one wire. #10 wire to the starter post as Lumbersawyer suggested above is as good as anywhere and better than most.
con: Voltage level is sensed at the stud on the alternator where the wire attaches and doesn't allow for any downstream voltage losses, so lights may be a little dimmer, etc. Many need to be spun faster than a 3 wire alternator to begin charging.
Two wire alternators Never seen one, unless you are talking about a "one wire" alternator with an output for the "ALT" light on the dash. Most one wire alternators have it.
Three wire alternators
pro: Has a "sense" wire that can be hooked into a remote area of your wiring harness. It will regulate to the voltage at this remote point instead of at the alternator itself resulting in somewhat brighter lights, etc. Many will start producing a charge at a lower RPM than a one wire alternator. All support an "ALT" light on the dash.
con: More complex to connect, 3 wires instead of 1 (or 2).
I use a 3 wire and connect the "sense" wire at the power input to my fuse box.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
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