I've used the Clarity ones for some time with no problem. The ADSL Nation ones are active rather than passive filters; whether this was the reason a neighbour had two of them fail, I don't know. They were replaced promptly and without question.
There is a review of some of the faceplate splitters,
which you may find helpful.
[EDIT] The BT splitter and the Pressac one sold by Solwise
are most likely the same as the ones sold by Clarity.
Perhaps someone more knowledgeable could tell us.
Edited by Tacitus (Sat 21-May-11 18:43:26)