Hi,
I got my Galaxy S since one year now, and after the first month, I discovered the joy of installing roms ;-)
I tried many many roms (probably 80% of the roms here) and my impressions were :
I was very impressed by Surface (stability, battery, smoothness)
but it has been beaten by Cyanogen 7 because of many features brought by CM and making the rom very comfortable to use.
I stayed quite a long time with CM, then I restart trying mods (because I wanted to have a full GSII look, but no GSII looking roms was stable and smooth)
So before coming back to CM7, I decided to try MIUI as it seemed to be as popular as CM7, and I falled in love with MintBerry 5see thread
http://forum.xda-developers.com/showthread.php?t=1350763)
I am completely stuck with it, and does not even want to try ICS roms because I am VERY happy with it for MANY reasons : stability, speed, tons of features, incredible dozen of wonderful themes, and best of all, all updates of the rom/themes/kernels/... are managed with a tool included, so you will not need anymore to play with odin and flash yourself.
Don't rely on the screenshots of the thread, because they don't show the magnificent themes (wood, metal, neon, dark, paper, pencil drawing, ...)
Have fun with the roms anyway, because it is great
And to avoid to loose your apps and have to re-install all of them, I would warmly recommend you to invest in titanium backup pro, because with it, you can backup your data AND the app included, so as soon as you flashed your phone, just "restore all", and after 10 minutes, all your apps are back with all their data and nothing else to re-install ! A pleasure !