Hacking Which firmware would you recommend for my TTDS nowadays?

[ShinraArmy]

DSLite and a first-gen TTDS.

 

[jurassicplayer]

DSTT only has one firmware...and sort of really just one kernel...the only thing you can change is the UI that you use, and for that there is no greater opinion than your own. Also, using any of the latter options besides the DSTT's default UI will require YSMenu and may or may not need to actually boot a ysmenu.nds (HWOS2, DSKiosk, and R4Menu will definitely need to boot a ysmenu.nds unless you take the long route and utilize mshl2wrap).
Options you can try:
DSTT default UI
YSMenu
Menudo
Moonshell2
MoonshellSimply
HWOS2
Dsision
Dsision2
DSCovered
DSKiosk
R4Menu (from spinal_cord)
etc.

 

[ShinraArmy]

Oooh, thanks for the suggestions!

I'm having problems running 999, Ghost Trick and Radiant Historia, anything for that?

 

[jurassicplayer]

I'm having problems running 999, Ghost Trick and Radiant Historia, anything for that?

Take a look at RetroGameFan's updates. Really all you need is the extinfo/infolib/savlib from any of the folders (and possibly ttpatch/ttdldi or w/e they were called), but feel free to spend time to actually know what you are doing.