Are Open Source Software Tools Better than Commercial?

For the first it's not easy to make quality evaluation of products that are often quite close and for the second, there are too many to make a significant test.

I think that there are some open source that are obviously very good (Linux, Apache, Eclipse,...) and I would tend to say yes for those (they are better) but beside, you can find some open source that are not good at all.

My point is that I think the question is too vague and it's not possible to say yes or no to that.

Some are better, some are not.

The anwer is: it depends.
Commercial software is very well supported with lots of documentation and help on debugging while open source tools are left sometimes "as it is". The one who develops commercial software tools is more responsible for their work, and this makes you feel confident in those tools.

To just look at I.D.E.s....

MS Visual Studio, supports C++, .net, VB, and maybe asp.

Borland's Delphi, C++, Delphi, and .net

Eclipse, supports every language and framework.

K.D.E.'s KDevelop, Supports every language and framework.
[ KDEStudio, commercial version of KDevelop ]

all have integrated debugger, all have integrated version control, all have tons of documentation. [ the open source docs in electronic format only, unless you print them off yourself, the commercial tools have hard copy when you buy them ]

in many respects, I would say the open source tools are better, they do not limit yoour language options like the commercial tools do.
the speed of fixing bugs or adding features in the open source tools is drastically faster, since if you find a bug you can also fix it. or if you want a feature you can add it and make either available to all users of the software very easily.

for bug fixing and tracking, bugzilla is far better than any of the commercial tools, it tracks all reported bugs and their resolution. anyone can report a bug, include stack trace and core dump data, and if they have the skill, the patch to fix that bug. all through a web intyerface so it can be tested by millions of people within hours of being posted.

the drawback for open source, Richard Stallman and his stand about proprietary code.