ORIGINAL: agexpert
Not that much has changed. There are just more choices. You can still run NiCD, but now you can also run NiMH, Li-Ion and Li-Polymer. You will be fine with NiCD or NiMH unless you want to save weight and get into Li-ions. There are some people using Li-po for RX, but that is just not something I would recommend.
The best battery is the one you are comfortable and SAFE with. Get a good NiCD or NiMH pack for around $10 and go fly. You can get fancy later on. I have over 1k in batteries and regs and that does not include chargers. Keep it simple for now.
Have fun!!
Plain and simple. Good answer too. Just get a good battery pack to use while you are exploring the options. I use NiCD's. But there is nothing wrong with the others.