It is best if you charge them with a proper NiMH charger.(posted 8881 days ago)Also watch out, there are NiMH AA cells of only 1100-1200 mAh capacity and NiCads with up to 1500 mAh capacity, so not all NiMH have more capacity than all NiCads.
Also NiMH tend to self discharge faster, so unless you are using your equipment on a regular basis you may end up wit dead batteries when you need them.