If you're considering selling your vote, go for smartsteem - they actively want to upvote good quality content, and have systems imposed to do so. But don't delegate to the bot. If you use their upvote calculator you'll see that delegating steem power seems to make more money. But they're not including curation, which means that you get 25% extra, on top of what they pay you. So it's worth selling votes as opposed to delegating.