I have all three of the tools you mentioned, so I can offer some insight.

First, the Leatherman Juice is a great pocket carry tool due to its size, but it is definitely not as strong as the Wave/Spirit and the handles are pinned so they can't be adjusted. They also don't have any locking tools, which can be dangerous, and none of the implements are designed to be opened one handed.

The Spirit is extremely well made, but again it can't be adjusted and the tools can't be opened one handed. They also are a little tough to open, but not too bad. On my old Swiss tool (non spirit) the lock was extremely difficult to work, which was something I never liked. I also didn't like that it only comes with a non-pointed half serrated blade.

The new wave has blades that open one handed and the one I picked up recently has user adjustable pivots (with a six-pin security torx bit). It also has easier to use with two liner locks and (basically) lock-back style locks on the other implements. The Wave also has an available pocket clip and bit adapter (to use regular bits). The Spirit is very nice, but I really think the new Wave beats it.

I personally carry a Leatherman Charge (with the upgraded 154cm blade) and I love it.