There are plenty of issues around AA rechargeable cells, but most of them are different in nature. The issues here is that the consumer really needs to completely drop the whole concept of "bigger numbers means better." A good rechargeable NIMH chemistry AA cell should meet a number of criteria. First and foremost, it should be fool-proof and trouble free. You should be able to just use them without having to "mess" with them to keep them working. They should be capable of holding a charge, at least for a few weeks/months above ~80% of the total capacity, and they should be able to do this even after heavy use and abuse for many cycles. They should be well matched in actual capacity and close to their label ratings right out of the package (after a top-up charge) so that the cells perform together well without causing problems.
So, with all that in mind, the standard recommendation from CPF, is Sanyo Eneloops (or one of the re-badges, do a search). They don't sport huge numbers on the label, but they are robust in ways that can't be described on a label with a simple number.
Keep in mind that the quality of the charger is just as important as the quality of the cells. Gets a charger that charges each channel individually with a smart termination method.
There are also li-ion cells in "AA" size, they are sold as 14500 size cells. You should probably avoid these unless you know where they belong as their higher operating voltage (3.2V or 3.7V depending on chemistry) will destroy most electronics that call for regular AA cells.
Eric