Here you need to know that ICO and pre-ICO both are different , here pre-ICO sell at that time when the coin is not yet officially launched and also the coin's project is not yet officially announced but the ICOs are when the coin get launched but not listed at any exchange , so here I think ICOs investment are better thing for the profit .
Perosnally I myself involved in the investment in many coin's ICO , but if you want invest in any ICOs then I would like to suggest you that you should go for the investment after the checking ICOs project perfectly whether everything looking legit or not  and project is better looking According to concepts of the coin ( here I am saying so because recently few scam ICOs run away with scam , so be careful ) .