Why is selectable better? Because you pick when it is locked. In a steering axle this is UBER important.
To generously practice what your life will be like driving in 4wd with a front locker, make every other turn that you want to. It sucks.
This means the trucks plows ahead when you want to turn, it means tight manuevers in 4wd can be kissed good bye.
Get a selectable front, your axles and the chance to steer will thank you.
Further, an LSD gives you only half the benefit of a front locker and all the drawbacks of crappy steering. A wheeling buddy used to have a TT, it worked well half the time. The other half we were aggravated. I traded a rear TT for an ARB. Currently another buddy is doing the same. There are selectable lockers and then there is everything else.