Regina is my chain of choice, although DID and Tsubaki are good chains also. Just steer clear of RK. I used to swear by them, but two broken chains in four races made me think otherwise.
2014 CRA Senior II and Buckeye Series champ
2012 CRA Senior II champ
2011 CRA Senior II and Buckeye series Harescramble Champion
2009 CRA Senior II and Buckeye series champ.
2007 CRA Senior II, and Buckeye series Harescramble Champ.
2003 Lonestar 250R
2001 Lonestar 250R.....now a 310
1986 TRX250R (restored to new)
1986 TRX250R (still in pieces)