Deniz,
I bought a Colibri this summer, it works very well as a logger. Convient to install and use. It's use for navigation is limited, though, since the user interface is 3 lines of text. It's real nice for flying a task, but not so good for where you are in general, or what are the nearest airports, etc. It does give winds, calculated by drift while circling, and ground speed and track.
The software that comes with it 'LXE' is usable, and is getting better all the time.
You could look at the Colibri manual at
www.lxnavigation.si
I haven't used any other logger, so can't compare.
Have fun