Might be worth getting a Russian Elmar clone (either Industar 22 or Industar 50) for the M2 or M3. They're cheap and pretty solid performers as long as you get a good copy (that's the tricky part). I picked up my I-22 from Fedka.com for $39 shipped and he hand picked a nice one for me.

I often shoot it on my IIIc, as well. And I have a Rollei 35S, which is a blast to shoot, but I often really wish it had a rangefinder. I've gotten competent with scale focus, and I enjoy its quirky controls, but don't find it slows me down at all. Don't have any experience with the Kodak, but you'd be hard pressed to pick a bad option from the other two.

A user-grade-cosmetic-but-freshly-CLA'd Barnack is a fine thing indeed, if you enjoy slowing things down a bit and really focusing on getting back to basics. Youxin installed a Japanese-sourced beamsplitter in mine, and now it has higher contrast than my M body, which he also CLA'd. The only caveat is that, while it's quick and oh-so-easy to focus, having to focus and frame separately is neither quick nor precise. So, if you're looking for a super-fast and convenient street shooter, you'd be hard pressed to beat an XA.

All else being equal, if I could only choose either the IIIc or the Rollei 35S, I'd go with the Leica, but not as my only camera.

And not to be a jerk, but in my opinion, if you're looking for pocketability, anything other than a 50mm on a Barnack is kind of missing the point (to whoever said it earlier), due to the limited 50mm VF window. Shooting wide-angle and hyperfocaling is a great way to negate the annoying split VF/RF, but you will need an accessory finder.

If size, speed and convenience: XA
If pleasure of fondling: Barnack with collapsible 50 (I had an elmar 2.8 LTM but it was really surorisingly heavy, so I sold it and got the I-22)
If size and usually color film, with no need for quick shooting/accurate wide-open close-range focus: Rollei 35S/35SE