bitcoin seems to have the least amount of features out of almost all altcoins, it's outdated and you can pay a 75 dollar transaction fee and it might take months for the transaction to be processed. The upside is that it is probably the most user friendly, has an established community and is the most well known cryptocurrency.
Ethereum has no cap limit. Massive inflation is sure to come along at some point and eth probably has the biggest potential to be manipulated. Possible train wreck waiting to happen.
bitcoin is the most mined and most accepted, these thing matter more than anythign else, all other altcoin are pump and dump, bitcoin is not really outded, it's just do the job, ETH is not accepted for now and probably never will be but has potential to increase very high