jellly bam is the best alternative rom right now?
or there are better one?  

try flashing a different kernel and see..

hmm, check the G version thread.

http://forum.xda-developers.com/forumdisplay.php?f=1550

find those with [KERNEL] tag..

i think its the modem/basebands.

never really played with them since i have good reception with the modems that came together with the ROM.

g version doesnt have good custom kernel. that kernel is based on codeworkx's aosp kernel. no touch sensitivity tweak unlike siyah.

still depends on ur usage. if it suits, then stick to that one.

you gotta try every possible kernels that are available for G versions..

some might give you smoothness
some might give you random lag/hangs
some might just be good for your usage.

maybe thats for stock sammy rom.

reflash rom with odin.

Samsung should spam less phones and stick in releasing only their flagship phones i.e Note and S-series along with like 2 budget Android phones per year.

Now they're like crap and releasing 2 phones every month, further fragmenting the Android ecosystem.

Because Samsung now is like Apple, it's like "THE" brand already.
In my college I can see more people using Samsung than Apple, maybe because of the price I don't know lah.

nope.
dont use odin.
now try flash back supernexus  in recovery
(it will replace installed kernel with kernel in supernexus )

else u need to
reflash stock 4.0.4 ROM
then start all over again.

download mode?

i think thats the only way

True, see the i9105? That phone is a waste of resource, totally utter rubbish. It's so similar, in fact, it's 98% the same except they used different materials for the back. 
The heck is with Samsung now, I better opt for htc or Sony next time, at least they won't release 2 phones every month.

Samsung, please keep it classy la, release min 1 phone and max 4 phones per year, and make every release as major as possible.

Just like Apple, (Not being an Apple fanboy or what) their phone are actually nothing special but because they only release once per year so the excitement and anticipation is there, and right after the announcement of their new iPhone every blog and tech site even Facebook is flooded with the news.

But what happen if Sammy release their spamming phones? Nobody gives a flying duck.

use triangle away: http://forum.xda-developers.com/showthread.php?t=1494114

ah crap. it only works on non-G. >.< that yellow triangle u got there is because u've flashed a custom firmware/rom with odin. (i guess..)