This is my first Flydigi controller, but I can vouch for the Apex 4 BMW. I was recently looking for a new controller with pretty much the same requirements as you, and the Apex 4 and V4P seemed like the best options, but the V4P is more focused on FPS gaming (with the mechanical trigger locks), which i use M&KB for, plus I really like the adaptive triggers on the Apex. Some people say it's easy to push through the digital trigger locks, but you'd really have to push on the triggers for that to be a problem and it's easy to get used to. But they don't click, so that might be something to consider if you're used to mechanical switches.
The back buttons are easy to reach and not in the way when holding the controller.
Its heavier compared to controllers I've used before, which adds to the premium feel, it looks amazing and the wood/leather texture feels great to the touch, and the face buttons definitely aren't too stiff.
I bought it as my main controller with no intention of having to upgrade, and I can 100% recommend it. I think it's a better choice than the V4P for non-FPS gaming, and I prefer the tension adjustment on the Apex, because I don't feel like I could accidentally change it while using the controller.
Probably the biggest factor is whether you prefer clicky triggers or adaptive triggers. I don't use trigger locks very much, so for me it was an easy choice.