Here's my first 5" in O3 (all the others are in Vista).
The JeNo frame (an open-source project) is perfect for it:
apex-style geometry and arms / no split deck / O3-compatible carbon cam plate.

It's a hybrid version of the frame (which comes in various versions to suit your needs): lightweight bus and basic arms, and I switched to a high-tilt (40°) cam plate.

As for the components, I'm using a SpeedyBee stack and FlyfishRC 2406 1950kv motors... the specs look really good, and I wanted to compare them to my FPVcycle 2506 1870kv. In the end, they're somewhat in-between the 2506 and 2207: a bit more explosive than the 25mm, but slightly less stable at low throttle. They're also much quieter and seem to consume slightly less power (they're lighter).

This should become my primary quad!

hope you like it!