In my experience anything name brand that isn't NCY seems to be a fairly safe bet. I've heard bad things about NCY but great things about Polini. They are always the most expensive and you usually get what you pay for.
I have to say on my 2012 Agility 50 I have installed a Kymco derestricted CDI, and a NCY Transmission kit but used 5.5gram weights instead of the 9gram weights that came with the kit (because I have lots of hills to ride everyday) and with 3,000+km on it already and 2,000+km on the NCY Transmission Kit. I have nothing bad to say about NCY as of yet. I am too also looking to go 72cc Enviromoto, NCY, or Naraku....Had a bad expereince with Malossi on my Daelim S-Five years ago but that may have been from lack of care on my part... as I was told they are good.
Thanks for letting me share!!!