Probably the best AA rechargeables now are Sany Eneloop batteries. They have good capacity, very low self-discharge and last a long time. They come pre-charged in he package. They are the best of the new 'hybrid/low self-discharge' batteries.
The 2500mAh Energizer batteries from walmart are disguised Sanyos, and are very good batteries. RC people have been building packs out of them for a while now because it's about the cheapest way to buy them. Like any normal/traditional Nimh battery they have a significant self-discharge, but even so they go several months in my cordless soldering iron. I use an RC field quick charger to charge them, so I don't know how long they last with the energizer brand charger.
Keep in mind that most low-self-discharge varients (like rayovac hybrids) have less capacity to start with, so that over the reasonably short term, you are still ahead to use regular Nimh's, because even though they self-discharge, since they start out with such a higher capacity (often 2500 vs 2000), that the quicker discharging normal cells will actually have more capacity than the low-discharge types for several weeks. Thus I don't like the hybrid types unless you need them to be charged out of the package (like the rayovac hybrids that I keep for my calculator backup batteries), or they are going in an extremely long-term, low drain application like remote controls, in which case I just use alkalines anyway. But Eneloops are good batteries.
Practically speaking, there is no such thing as memory effect, even with NiCd batteries. It's practically impossible to produce memory effect without deliberately trying, and with expensive equipment. You should never purposely drain your batteries before charging them whether they are NiCd, Nimh, or lithium. Doing so is just wasting their useful life away on needless discharges.
