If that great, all-analogue octaver sound is what you want, there are plenty of solid units to choose from (OC-2, EBS OctaBass, Foxrox Octron to name a few), but the Octamizer is a great pick due to the tone shaping capabilities and the fantastic tracking. It's the right one for me, because all I care about in an octaver is good tracking on single-note octave-down, but I also like to be able to shape the tone. In case you missed it, I did a review of the Octamizer
here. I've never used the OC-2 or OC-3, but keep in mind that the OC-3 is digital, not analogue, and anything you read regarding the OC-2 likely will not translate to the OC-3.