Not so sure if Nano tanks have a good quality T5 setup available but it depends on what you want to keep. Are u going for SPS, LPS, Softies, or a mix. The most lighting required is with sps then lps and then softies. Of course this addictive hobby you'll probably end up having some sps but some have preferences.
Decide what u want to keep and go from there. IMO MH or LEDs for nanos are great and you'll get the shimmer. MH will run hotter and consume more electricity and LEDs just the opposite. Think about your conditions and read read read...