Ask HN: Which continuous integration/deployment solution do you use and why?

I am the co-founder of www.shippable.com and we're trying to understand what people value the most while choosing a continuous integration solution.

Our hypothesis is that it's complexity, speed, and price so we're focused on making our product super simple, fast, and cheap.

But just wanted to get additional thoughts from folks here- - Do you already have CI set up? - What were the top 3 reasons for choosing your existing solution? - What value prop will attract you enough to switch?

Thanks!!