I admit to not being familiar with any of these particular bibliographic reference tools and that in itself is a bit of a wake up call. In my defence though, during my first degree the whole course was hand written [yes, it was THAT long ago] and my dissertation was typed up by a friend [can you believe that?]. During my MSc [Library and Information Studies] I probably would have been able to use one of these tools or something similar but at the time I wasn’t sufficiently aware of them [I’ll never forget how difficult and time consuming sorting out the references was and I spent many a dark hour in front of the lap top on the verge of frustrated tears trying to catch and pin down that develish data as it swam before my eyes; happy days!].
As it stands, I currently have no need of this kind of reference management tool but I am more than happy to familiarize myself with it so I may impart the knowledge if needed. However, time is short and I am fully aware that there are some incredibly conscientious people that have actually finished the CPD23Things [yes FINISHED and ON TIME]; so for this reason, I am only going to look at one of these tools.
In order to choose I took CPD23 advice and looked at two citation reference comparison documents; the first by Martin Fenner was quite helpful but the comparison table on Wikipedia was just too much for me [take a look for your self – far too much information in one small area]. Next I watched the three introduction videos and from these I ended up choosing to look into Mendeley [although I thoroughly recommend Library Wanderer's witty [and well written] post extolling the delights of Zotero].
According to the Mendeley website, it seems to cover all bases with regards to general referencing needs plus I also found this informative comparison table. I think the free space is a tad limited compared to some of the others but to purchase an upgrade is reasonably priced. However, it is limited in that it’s a desktop application only and there were comments on the website asking if there were plans afoot to introduce a portable version. The next step would have been to download the free version but since I have no need of it at present and time is of the essence, I’m leaving it there.