I bought my first picks from these guys. I bought one of each of their tensioners and one of each of their picks. You will be glad you have.
However, these are all basic tensioners. You will find that they lack in the ability to grab the top of the keyway very well, except for two, and those are the oddly straight (180 deg) twisted wrench, and the wishbone. It may also help to modify a couple of your wrenches, shortening the bit you insert into the keyway, so it doesn't go in as deep.
I would recommend buying Peterson's Flat-Five or Three-Serrated or both from
http://peterson-international.com/tensiontools.htm . They each have serrated teeth to grip the keyway better.