[garenp]

Of the CI tools I've used (most of them) TeamCity was my personal favorite--but the advantage of Jenkins is that it's very widely used, has a greater breadth of capabilities due to the huge plethora of plugins, and a huge amount of support info readily available online. Some plugins are even maintained by an external vendor that produces the tool you're trying to integrate with and are either better supported or the first to get timely updates.

Bamboo on the other hand is IMO the worst of the commercial CI tools by far and where I work has gone down for us the most. Atlassian itself doesn't appear to be investing in it much anymore judging by the slow pace of development in recent years and at their most recent conference, you can hardly find it mentioned or see much presence for it anywhere.

In all the CI systems I've used though, there has not been one that I haven't encountered some major difficulties with.

Beyond that, anything to do with build automation for a large number of users always quickly becomes a support & maintenance quagmire. Users frequently want to install a new (barely maintained) plugin to solve a problem they have, complex interactions lead to difficult to understand failure modes that require time consuming investigations ("your CI tool is the problem and broke my build" ... "No, your build is broken" ...).