To decide about usefulness and usability, it is necessary to know all of the followings:
1. About the license
Even if you can personally afford to pay for a licence for software you may wish to share your methodology with other students or researchers who cannot afford to buy a license.
2. About the ease of use
If the software requires the help of an engineer each time you need to use it, this will be a serious limitation on your usage.
3. About the strengths/weaknesses for specific annotation purposes
4. About the type of data or analysis the tool/software is designed for
When annotating corpora at multiple linguistic levels, annotators may use different expert tools for different phenomena or types of annotation. These tools employ different data models and accompanying approaches to visualization, and they produce different output formats.
(Chiarcos et al. 2008)
5. About its compatibility with other annotated data
Highly reliable manually annotated resources are, naturally, more expensive to construct, rarer and smaller in size than automatically annotated data, but they are essential for the development of automated annotation tools and are necessary whenever the desired annotation procedure either has not yet been automated or cannot be automated.
(The Clarin User Guide)
Most of them are:
free download, Windows only
Fully-automatic or semi-automatic (with a procedure outcome report)
Designed to be able to deal with spontaneous speech
No limit of the corpus size