I'll stick with NiMH batteries because that's all I use for tanks, and what I gather most of us use as well.
They are not AS sensitive to charge / discharge cycles as NiCad or even Lipo batteries are and won't go bad if you top them up a few times in a row, that is to say their charge memory isn't very strong. They CAN develop one however, so a discharge whenever convenient is a good idea.
With storage, again they aren't prone to issues. I don't really store mine fully charged or drained. Charging them up in the days before an event has not given me any issues, and I often leave the batteries half drained inside their tanks for weeks.
One thing I do is to have a rig with a Tamiya plug and two 12v turning signal bulbs hooked up in parallel to quickly drain the batteries down for a full charge cycle. It's faster than the de-charge function on my charging unit, and won't hurt the cells.
Tiger I - Panzer III - Panzer IV - Chi Nu Kai - Panther G - KV-1b 756(r)
M4A3(76) Sherman - T-34/85 - M3 Grant