The Air 3S is a significant upgrade over the Air 2S. I think I would take an Air 3S over a Mavic 3 Classic. A Mavic 3 Pro on the other hand is a more difficult question. If your main goal is photography/videography, the cameras on the Mavic 3 Pro...
The best backup is another copy of what you already have so I'd say another Mini 5 Pro. All your accessories are interchangeable and if you crash one then that becomes a parts bin for the other. If you really want something different (or cheaper)...
Global mini 3 pro IFB specs*
Capacity
Intelligent Flight Battery: 2453 mAh
Intelligent Flight Battery Plus: 3850 mAh
Weight
Intelligent Flight Battery: Approx. 80.5 g
Intelligent Flight Battery Plus: Approx. 121 g
Nominal Voltage
7.38 V
Max...