I have an apex classic and love it. Really let's you hone in on your tanks day to day health and also gives you tons of control with automating things.
In case you missed it, at MACNA they neptune announced an apex compatible water testing device for alk, cal, and may. This device will only be compatible with the new apex. If you plan on getting that, the unit itself will cost 500-600 over the cost of the apex. If you can do without that device, I would get a used classic, because there's about to be a flood of them to hit the market