If there is any other alternative i will be in support of, that will be Waves and NEO. I think these two have the potentials and they are gradually coming up, but saying that they can totally substitute Ethereum is a no to me. I think ethereum will continue to be relevant and will be used by most projects. Notwithstanding, others will also gain more relevance as time goes on.
Waves could might be a rival to Ethereum though there is not that many people using it. Namecoin is another coin that could compete with Ethereum eventually.
Yes, waves is also a platform but very far compared to Ethereum in terms of innovation and adoption. I think there are also implementation in XRP, Stellar and XEM but it seems lack the publicity. Ethereum is by far the most used, popular platform within ICO's being used.