The OX and ARB are the two most proven selectables, with the e-locker fairly new on the scene. I've read and heard about people having some problems with the early e-lockers, I believe these problems have been addressed, but definitely dig deeper until you're comfortable that it's a reliable choice.
The first thing you have to prepare yourself for is the cost. ARBs and OXs run somewhere around $700-$800 each. They also require either an air source (ARB) or cables, which cost extra. ARB's electric compressor runs around $200, OX cables are about $100 each. With the ARB you can use an alternate air source, your factory A/C can be converted into a much better compressor than the ARB or most other electric ones, one capable of filling up tires and running air tools. OX also recently introduced air and electric actuated modules in lieu of the standard cables, I don't know much about these, but you can bet they won't be cheap.
If I could do it again, I'd go ARB front and rear and use my converted A/C compressor as the air source. While I've generally been happy with my OXs, the front cable is still a bit intermittent after several adjustments. I've talked to others who've had zero problems getting their cables and controllers adjusted, some others who have. The ARB requires no adjustment, but is a more involved initial install with drilling the airline hole in the top of the diff and getting the copper airline routed properly on the carrier. I wouldn't recommend either locker for a shade-tree mechanic to install, get someone experienced to help or pay a shop.
Bottom line, plan on paying a bunch of money for either set-up. But it is very nice having strong, dependable lockers that can be turned on and off as conditions warrant.