Which COIN do you think has a long term good fundamental future? Despite the TOP coins, that you think has strong team, model and in long term they will create the value.
Bitcoin must be the only coin I do consider a fundamentally strong one even you are not considering it, I need to mention about it as it is still enjoying the top position in all kind of ranking related to cryptocurrencies due to its all fundamental characteristics. Probably you are looking for penny stock to get multibagger returns but you cannot ignore bitcoin when you are considering long term investments. I like to suggest you to go for investing with bitcoin for more than 50% of your total portfolio and then you risk with any other fundamentally good coins.
That must be a good suggestion because you cannot build a good fundamentally strong coins based portfolio without bitcoin. In my opinion everyone should go for more than 80% of their total capital amount and not just only with 50% unlike you have suggested. Because, when you are going more with bitcoin investment with very long term holding plans like for next 5 to 10 years then there will be different possibilities for cracking big profit rather than risking with unknown coins and then losing with them.
Building a Portfolio based on fundamentally good coins must be a good idea but ignoring top coins for that must be a very big mistake in my opinion.