The Zeagle Flathead VI and Apeks are very similar. I currently own a couple of Zeagle Flatheads along with a bunch of other regs. I previously owned a couple of Apeks. The main difference between their first stage designs lies in the fact that both seats (hard and soft) are replaceable in the Zeagle. In the Apeks (as in most other diaphram regulators) only the soft seat can be replaced. If anything happens to your hard seat you have to buy a whole new body. As far as second stages, their designs are very similar. The Apeks offers a choice of exhaust covers and IME, the Zeagle breathes drier. All of my Apeks seconds breathed damp when the exhaust valve was above the mouthpiece (if you tipped far enough to side or were upside down). Both can be tuned to breathe extremely well. The Zeagle is made in the USA and their lifetime warranty has fewer limitations than Apeks' warranty. Apeks has a larger following in the tech diving community. Usually, the Zeagles can be bought at a lower cost.
Jackie
Jackie