Ping. Although I have reverted to the I25's to good effect. As I've said before, I would be happy to try any brand and if it worked better than the clubs I have now (I25 or I series) then I would have to consider the change
Mizuno MP20 HMBs with KBS C Taper Lite shafts. Love them.
I've had Regal somethings, Golden Bear somethings, Yonex somethings (post appendix surgery, I couldn't swing steel for a while, so went graphite to get back to golf quicker!), Mizuno MX20s, TM R9s, Ping i25s and the HMBs.
The MX20s are my favourites though.