I run ARB front and rear, and I love selectable lockers. They give you open diffs on the road, which means they are invisible, but at the flick of a switch, you have lockers. I have also heard good things about the OX lockers, for much the same reasons (although you dont need to run an air compressur to run them), but you need to be sure the cable is installed correctly; otherwise, they will not engage properly.
If your Jeep is a DD, I would stay away from selectable lockers, but many people run them and learn to drive on the road with them (it's a personal preference thing). But, in general, selectable lockers do have some odd road manners.
As far as the ECTED and lunchbox lockers, I would not recommend them; first of all, most are not lockers, but rather limited slip, which means that they are a kind of middle of the road type of thing, and you will not get the best of either the open diffs or lockers. Second, those that work on clutches tend to wear out, which means they start becoming less effective with time. But again, it's up to what you like and dislike.
I am sure you are going to get MANY opinions on this thread, and my advise is consider what you want to achieve and then weight the opinions here based on that.
HUH?
Get a selectable if it's a DD and there's a possibility of snow on the highway. There are selectables that are either open/locked or open/limited slip. Selectables are generally more expensive, but they do have advantages. Selectables will require more skilled labor to be installed but will be stronger than a lunchbox locker.
I had Lockrights front and rear in my XJ and drove it all the time on the street and highway, you just have to know how to deal with the handling quirkes. A Lockright IS A LOCKER. A Detroit Locker is also a locker, naturally. A Detroit and a Lockright work fundamentally the same, only a Detroit comes with it's own case that is designed for the added stresses of being "locked". A Lockright can be installed by the lay person because the gears will not have to be "set-up". Since a Detroit comes with it's own case, the gears will need to be set-up, an additional cost and should be done by someone that has the know how.
If you are forced to decide between the front or rear being locked, the rear is always a heavier duty axle, and also does more work that the front. Where then does it wake sense to have a "traction aid".
Take your time and do your research.