Been tempted to pick an S6 up sim free lately. Coming from an S2 so any new phone will be a massive upgrade, just concerned about the battery life as I haven't read much positive feedback about it. Also half wondering if at this point I should just wait to see if they actually announce the S7 early in January as rumoured.
Battery life will hopefully get better with marshmallow. It's the standby time (when the screen is off) which is really crap on mine, and marshmallow is said to improve this aspect of the battery life.
The only thing about waiting for the s7, is that it will be a while away even if it's announced in January.
Also, the price of the s6 currently is fantastic. Can be picked up easily for £399. There's no way the S7 will be near that (not until this time next year anyway!).