What kind of driving and wheeling do you do most. Lunchboxes are the cheapest and a detroit is bomb proof but A selectable in a shorty is gonna be best if you do a lot of street and for sure if you drive in snow. Air requires a on board pump to work. That is a good thing if you want to air up your tires too but it adds extra cost. Electric is maybe the cheapest install but the ARB is generally accepted as being the strongest of the selectable's. Axles are really going to depend on tire choice and how hard you wheel it and where. Rocks,mud,trails all have different requirements. I am guessing that you have a 30/35 combo in there now. We need more info and then your going to have to sit down ad go thru about 10 different opinions on what is best. Good luck.
RK 3.5 X factor w/ 2.0 RK shocks and T/F Speed Bumps, Currie Correctlync with flip, EVO under armor, 44 Magnum sleeves and gussets with JPI t/case skid, Rock Hard evap relocation, Tom Woods 1350 Driveshafts, 4.56 gears, Viair OBA, AEV rear skid and Pro Cal, RCV axles, 35" KM2 tires on 17" MB Black Razors, Cobra 75 radio. RSE electric sliders, SPOD.