If you mean the standard one (Not the new M68 one for the 2" and new 36mm filter wheels) I prefer the QHY OAG-M, the ZWO one resembles the Thin OAG which I found not to be rigid enough.
Hi Karl
I migrated to the ZWO OAG which markedly improved guiding. If I had the money I would get a helical focuser and the ASI290 for the OAG which would help focusing from time to time.