Alkaline AA cells have roughly 3 times the capacity of a standard AA NiCd and about 2 times the capacity of a standard AA NiMH.
There are high capacity NiMH AA cells that have nearly the same capacity as a Alkaline (4 watt hours), but you will pay a premium for them.
Some issues - NiMH and NiCd batteries are capable of delivering more current (milli-amperes) to a device than Alkaline, which might damage a poorly designed device. And as mentioned they can deliver a lot of pulses in a hurry - to the point where the battery itself might get hot and the heat might damage a device, or the sheer number of pulses in a short time might damage the device.
So if you use rechargables be aware.