I prefer Tomato 1.23. 1.25 seems to have some issues, but 1.23 seems to be rock solid. I'm using the Victek mod.. That guy is just amazing.
What kind of issues, 1.25 has been rock soild for me on my WRTSL54GS (man that a long model number =P) -- AMD Phenom II x3 720 BE @ 3.5Ghz(OC) | 4Gb Memory @ 1600mhz | Sapphire ATI HD4870 1GB 800mhz/1000mhz(OC) | 2x500GB HDD's Raid 0 | Windows 7 Ultimate x64 Build 7100