Best version of OS X for a 2008 iMac? (This is a follow-up to How to improve old, slow iMac -- new SSD? Or more RAM?)

I replaced the HD on our old 2008 iMac 8,1 with an SSD, and it seems much faster.
However, it was running 10.9; now it's on 10.7.4 (which was already on the SSD.)

Should I install 10.9 like the App Store suggests? Or keep the version at 10.7.4?

It only has 3GB of RAM.
I am of the opinion that you should keep your O/S up to date unless you have a SPECIFIC reason to stay at an earlier version. E.G. incompatible software that you MUST run or a noted incompatibility with a service that you can't do without (EG some people are still having issues with MS Exchange compatibility in mail.app on Mavericks).

So, your computer has enough RAM (more RAM if possible) and a nice fast SSD so I would go with the Mavericks install... IMHO