Do you think cardano will over take ethereum in terms of tech with voltaire being worked on this year. Along with erc20 converter for easy conversion to cardano via ethereum. 
There's a high possibility for Cardano to take over the top spot only if ETH will remain slow and expensive.Its actually hard to tell because many are still using ETH network despite of the issues with the fees and the slower network. Honestly, I don't want to choose because I believe both of them have a bright future so better to hold both than to choose on which one is better, time can tell but for now ETH is still the top choice of many.