I sold my TTi shortly after I got the Arc. I don't miss it. The Arc does everything I want a Leatherman to do, and it's easier to use. New blade profile is great, outside opening tools, one hand use, good toolset for me - it all comes together. It solves all the little problems and annoyances I had to work around with the Wave and Charge. The Alpha looks like it makes sense as an upgrade if you really don't want the Free system, or if you like the G10 handles.
The Micra is the keychain-sized scissors-based tool, and it's the only small one they make anymore. I got one for my wife. It's well made, but you can do pretty much the same stuff with an SD Classic in a cheaper and smaller format. The Squirt line was their keychain tool with pliers (or wire strippers). Sad to see that one go. The Juice series was intermediate in size; I never got to use one but people seem to have loved them. Can be found on the bay, if sometimes for exorbitant prices.