steemrewarding.com I'd have to say is one of the best auto-voters around, it provides features for Trails that I couldn't find with any other tools. It allows you to either follow anyone's curation upvote trail, downvote trails, or vote for all posts and/or comments posted by specific authors (with a lot of different rule parameters to choose from)

FYI: You don't need to 'activate' a curation trail on SteemRewarding, you can set it up to follow anyone's vote trail regardless if they have visited the site before.

[For those of you in Asher's Engagement and Curation League and who are going for the Spot Prize, be sure to set up all your trailing rules to EXCLUDE posts from you as an author, or you'll end up with an accidental self-vote possibly ;) ]