Used to run nothing but SMCs. I needed a new battery last year (and no SMC batteries to be had) so bought a CRC Rocket Fuel 7500 and it was pretty good. IR numbers down to 1.0 on my iCharger 406 DUO and voltage numbers under a 40-amp load that were nearly as good as my two-year old SMC 8300.
My 9-year-old son got more heavily involved in 1/12th scale this past season, so I needed another battery. I was going to get an EAM 7500, but they were out of stock. Everyone was talking up the brand new Tekin 2S batteries, so I decided to give the 1s 7400 a shot and holy heck, it's a good one. IR numbers down to .7 on the iCharger and voltage numbers that are on par with the CRC battery 2-minutes earlier in the discharge cycle on a 40-amp discharge - meaning that, if my CRC is reading 3.9 volts at 4 minutes on a 40-amp discharge, the Tekin is reading at least 3.9 volts at the 6-minute mark.