No one want bots or software, every want human activities, why you go with twitter. Human Activities is the better than Bot. Use this
I use autotwbot. It's great for startup accounts, though it won't add thousands of followers instantly, twitter has a restrictions on connections. Why I use autotwbot is because its a desktop software, vs using a website. Though it works a little differently then what I've seen. It's based on a timer, so the software will do some twitter tasks automatically every time timer goes to zero. Then it restarts again, this way it's always doing stuff all day long vs doing a big batch of task. At first it's slow, though after a few days of running it in the background you don't notice it and you get good human followers. If you want to process more followers with autotwbot you can just adjust the timer to 1 minute, though it doesn't seem to run smooth if you have a large account. I use 7 minutes. Also this way when I log in my twitter account I can respond to mentions and message manually to make it more personal at a good rate - if I get 1000 in a day I cant respond to anything. Any how this could be down your alley - check it out by googling AutoTWBot or autotwbbot[dot]com Let me know what you think Cheers