Two very different protocol layers, and both are honestly very early stage. At the moment I think the only protocols worth building robust business applications on are Bitcoin and Monero. Ethereum is too risky- I would not invest a half million EUR in a business solution/application that runs on ETH, because I have no idea what is going to happen to that thing next month and my maintenance costs could go through the roof depending on how it goes.
That said, there are limitless opportunities for building crypto applications. Starting simple is the key, people in crypto tend to forget very quickly what state the "real" world is in. I think a big opportunity right now for consumers/merchants is a "quickbooks" style business solution; an all-in-one payments/accounting system for entrepreneurs that want to accept crypto payments. Use a shape-shift style integration and accept all different crypto payment methods to future proof it.
More mobile wallets for consumers are needed, and if you can gamify them or make them otherwise interesting and/or really easy to use all the better.
