I would definitely but both because diversification is actually a good thing in Long term. I will divide my investment by 33% to Bitcoin, 33% to ethereum and the remaining 33% to different altcoins and ICO's.
I agree with your 33% of bitcoin and 33% for ETH but if you ask me to give you a sincere advice then brother dont go for other altcoins or ICOs. They are not profitable even now so how can you imagine they will be profitable in next 5 years. Yeah ETH and bitcoin will have an amazing future so make it like 45% for each. Diversify your investment and have a great life.