I would say that investing into the bankroll is much better since you actually have bitcoins (or whatever altcoin you invested) and can withdraw it anytime. Unlike if you buy ICO tokens/coins then that means you will not be holding bitcoins but that token/coin. In case you want to liquidate your investments you have to sell those tokens or coins to an exchange, which could be far less than what you paid for them. Generally, the problem is that the tokens/coins are subjected to the volatility factor of any altcoins.