One of the best upvote bots I've found recently has been the 
This bot currently accepts .05 SBD for a 5X bid once every three days, which is quite a wait. While I wish I could get an upvote more frequently, I think it is good for the bot to limit the number of times someone can use it. This ensures that the bot maintains a high enough VP to allow continuous voting and can help promote content consistently.
I would highly recommend checking out this bot and putting its services to use, I know I will be over there every three days to get my upvote.