I've tried a few different multi-tools, and the one I came back to (and bought several of to keep on different bikes) is the
Topeak Hexus II
It has just enough tools to have all I feel the need to carry, but not so many that the tool becomes too bulky to use in tight areas. Also, the tools (and body) are a little longer, so that also helps (along with the narrower profile) in getting into some tight spots.
I really don't care much about ergonomics, that has never been an issue with any multi-tool. The real issue for me is whether it can reach what it needs to and have room to turn. And in this capacity, the Hexus has always worked. I rarely ever use the tool on the road (mostly seat post/saddle adjustments as I am tuning the fit of a bike) but they do see a lot of use on the mountain bikes (either mine or someone else). I have never not had what I needed, and it always seems to fit into wherever needs to.
Sure, it is not as easy to use as individual tools, and I don't use it in the shop, but it is very compact, light, and most importantly it keeps all the tools together with very little to get lost.