Try some to see how they work for you. It doesn't take long to flash them and then test for your location.
I was 22.214.171.124 but it didn't work very well indoors. Now, I'm using 126.96.36.199 and it seems to work better overall including indoors. Of course, this is my testing results and may not work for you in a different location.
Check out the radio thread in the rom section.
Device: HTC Tilt2 (TP2) on AT&T (Oct. 2009 - )
WM 6.1: Cosmik Debris 4.2
Android: MJG Rhodium Android
WM Shell: SPB 3.5.5
Hard SPL: 0.85 OliNex
Unlocked: Sim, CID + Security
Radio: 188.8.131.52 (works great indoors)
OperaMini 4.3 + 6 Esmertec Jbed, Comic Reader Mobi,
Opera 9.7, Pocket Player, CorePlayer, Slingplayer 1.6,
HTC WiFi Router, Google Maps, Pocketwit, Fring SIP,
Tarkim Keyboard Controller
Retired: Cingular 8525 (HTC TyTn)(Nov 2006 - Oct 2009)