buying after ICO is the best for me, most coins getting dip after the distribution of coins after ICO and later on will pump up higher that ICO price. But it is not always the case so watch out for good ICO out there, analyze them hard so you can choose well.
There are tons of ICO projects around sometimes its very difficult to predict which one will be profitable going forward. That's why I always trust my gut feeling when it's time to make a wise decision before investing.