is that really so hard and everyone have to ask about the combination?
android is about exploring, and different ppl have different taste ... u need to get off ur comfortable seat and start exploring, i am sure those who flashed had no idea before they flashed ... and common sense, if u wan something that fits for the 1st time, then get all asia stuff (asia csc and modem) ...
having the same csc/modem with some other forumers doesnt mean u will get the same results as them ...

You can wait for nasrulbond to reply. I think he is experimenting with different modems.

As for me, I flash a modem and use speedtest app to check edge speed. For gps, I go out for a walk and test how accurate and if it can mantain gps lock. Since I don't live in Msia, my result may not be not as useful as you guys like.

For csc: I doesn't really matter. Only difference is the apps that show up in Samsung apps.
Kernel: I have been switching from SO and speedmod back and forth on different versions. I can say I have been getting consistently better battery life and smoothness with speedmod kernel
Modem: I use JPP modem with better result than JPY. Of course, you willl have to make your own test to see which one suits you the best.
Apps:
- Browser: JS3 broswer has max 4 tabs but is hardware accelerated. JP6 broswer is 8 tabs max but with no hardware acceleration
- Launcher: GTG TW is nicer than samsung's. It's good to have at least two launchers as a fallback.
- Keyboard: I love gingerbread KB and swype. There's a modified GB keyboard posted in this thread. I'll find the link and post it here. addon: Here http://forum.xda-developers.com/showthread.php?t=845162 I use the wp7. the  stock green FC on me.
- Get fasterfix so that you can connect to a nearer server (asia)
- LCD density changer. IMO insanity rom did a much better job with its multidpi apps. I set it at 200dpi
Themes: I use generation-x a bluish theme

Hope this helps

edit:spelling - typing in the dark sucks