If your going down that route, I believe 2.2(froyo-(frozen yoghurt)) should have multitouch and apps2sd or link2sd built in. As for whats more stable, ive only tried cynogen so far, im waiting on a delivery of some new sd cards (one each for me n the mrs) before i try 2.2 again.
What got me the last time was that after ever reboot of the phone, i had to tell it to use swype as my keyboard, for some reason it wouldnt retain the setting as default. But that could have been down to installing cynogen over the top of samdroid, next time it will be a clean install. (2.1 JH6 flash > root > cynogen kitchen)
Cynogen: or at least 2.2, does seem to have a whole bunch of extra preferences and settings though. Much fun to play around with. And of course you can get a bunch of different kernels if you wish to overclock the CPU from 800mhz to upto 1.2ghz i believe.
Samdroid: im assuming will pretty much be the same as what i already have, with the addons that 2.2 brings, not sure how stable it is, but it might be worth you looking over at forum.samdroid.net for yourself and see what bugs are being reported/fixed with all the mods, not just this one.
Spicagen: I get the impression that this is a dedicated spica kernel/rom and as such has been streamlined and recoded for the purpose and as such gives a better linpack / quadrent benchmark score without any over clocking of the CPU, and thus also increasing battery life (maybe) alone with the 2.2 updates this could well be a pretty sweet option to go for.
You might want to also consider the new 'in thing' called 'all2ext' i think that this basically puts ALL of the firmware and cache onto your SD partition (as long as its big enough 512mb+ probably)