Which should I buy, WAVES or ETH?
If your not sure which one to go then it is always good to go with both coins because of waves and eth are good coins. You can reduce your future losses when you diversify your funds.
If you have to ask a question like that and you put it in those terms, perhaps you shouldn't but either of them. Or, alternatively, just flip a coin without waisting your time and ours with questions like that.