I would take the first step and go with Dawn, as the latest Phoenix seems to be still under heavy development and is in fact up, from 1.6, to 1.8

Those using the alpha releases may have other ideas though :)

I suggest : 0.9.1
That is a very stable fast version. The best.

I use 0.9.1 for my main ezine/blog and 1.6 for the one less consulted.
1.6 is not smooth enough yet. That is why it's an alpha version.
But if you're ready for a bumpy road, 1.6 will bring you to eternity.

I upgraded to 1.6 and then 1.7CVS and completely recommend using .9.1 instead of 1.6. Upgrading to .9.1 shouldn't be very time consuming especially since your skins will mostly work. Going to 1.6 means overhauling each skin AND the blog. Your hacks MIGHT not transfer to .9.1 that easily so search the forums for some tips and tricks about functions that got renamed (or whatever), but they sure won't go into 1.6 very easily given the complete overhaul of the file structure and naming convention.

As to spam control, .9.1 is way better but not a silver bullet. One thing it does is to shut out spammers as soon as the page starts to load instead of waiting for the end of the page. This saves your server a lot of useless work. There are many other spam-related improvements though, so overall it is the best thing for your purposes.

Oh and on your skins: publicly displayed stats went away in .9.1! disp=stats means nothing in the new world.

Why did they remove stats in .9.1? Is there any way to bring them back?

The reason was to send a clear message to spammers: don't bother because the stats don't get shown. I think they're recoverable if you want but I never did it and don't have an installation handy to play with. Coupla days and I'll probably be toying with it again just because. Praps someone will beat me to it?