If your goal is to one day trailer that bad dad to the race track most of the time, then build for the future and grab the locker. Could be a bit of a nuisance on the street, but you'll be set without having to go back in there.
That said, any of them will work. With the locker, you're one step away from a spool, but with the benefit of unlocking when you're done and need to turn off the track. If you're not going to spend most of your time at the track, and more on the street, I'd move that button choice up at least one. +2 on
melloelky recommendations.
Get the Truetrac or traclok for the street. A traclok is basically a clutch posi which deals with friction modifiers for the clutches. Truetrac just needs rear end lube without extra crap in it since it's a helical type posi.
IMO, a locker type is better suited for jeeps and four wheelers when rock crawling, etc., because the locker drives the wheel on the ground as you lift the corner. Truetracs won't do that. If you're going to push gobs of torque at it for racing, a locker may be exactly what you need.
How's that for a non-answer?