reeftek or geo. i'd also consider an MRC if you could find a really good deal on one used. or barr (now austin oceans) if you can float the extra money. i just saw theirs comes with a flow meter which is nice and helps justify their price (or you could add one to any unit for ~$90 like i did to mine). you don't really need the flow meter, but it is a whole lot easier than counting drops. i used to think ph controllers were unnecessary (a good regulator should hold a steady bubble count) but after mushing media a few times from the effluent rate slowing down for whatever reason, i now would not consider running one without a ph controller. the milwaukee works well enough for cheap.
i really like the idea of the deltec being fluidized, but the grit it forms is too much wear and tear on the pump and their media is *way* too expensive. i think the schuran is junk, all of it's fancy features they brag about are there to correct a base design flaw- excess co2 bubbles in the body that don't want to dissolve from not running the body under pressure. a proper system doesn't have all those undissolved bubbles to begin with, so they don't need a complicated bubble collector on top to separate bubbles from liquid, just so the oversized recirc pump needed to build up enough pressure to suck those bubbles into a venturi, since they would stall the pump if they were simply sucked into the pump inlet like all other reactors do.