It depends what you want to do.
If you never envision yourself using TTL control, then just about anything will do (though you might find the YN462 to be way underpowered compared to the other units in the lineup). For the sake of versatility, you might want to stick to the higher-powered units (either "mark" of the YN560) just to make sure you have power to spare when using modifiers (umbrellas, softboxes, and so forth). The YN460 is also a good choice, but with less power (Photoflex and others sell the YN460II rebranded in North America for about $150 or so, which is a bit of a vote of confidence). Note that the colour has been reported as being a little bit bluer than average for a flash, but that's fixable with a 1/8- or 1/4-cut CTO gel (about six or seven bucks for a 20x24" sheet that'll last you the better part of a lifetime) so getting it to work with the Canon is not going to be a big problem.
If you even think you might want to try TTL shooting at some point (and there's much to be said for TTL), then the YN565EX (for Canon) is probably what you want. It will take orders from the Canon flashes (although the Canon flashes won't take orders from it). It will function as an E-TTL flash on camera or with a remote cable. And it still has all of the manual functions of the all-manual 460&560 models and power similar to the 560. The only drawback, really, is the price; although it is a far sight cheaper that a Canon-branded flash, at an eBay price of around $150, it is quite a bit more expensive than the all-manual models.