on the top right of the page: https://smartsteem.com/

there is a calculator now, just enter the same amount for the vote selling as you would delegate and see the difference

If you delegate and undelegate a lot then just sell the votes, if you want to delegate and just let it ride then delegating is going to bring more
I personally have a bit delegated but prefer to use vote selling just because that does not take my voting weight away from me. For the moment also only the vote selling is selective and makes it so that I can set it up to only sell to whitelisted users