If your gen 1 are already excellent for you, there’s no reason to upgrade, same as there’s no reason to get a new phone or laptop every year. My wired headphones are ten plus years old and will be fine for a couple more decades; my gen1 Max, at a fifth the price, are also fine and will be fine until their Bluetooth becomes too old (which may be ten or twenty years these days). Both benefit from earcup swaps occasionally (but gen1 lightning needs them more often than usb-c.)

If you’re unsatisfied with Transparency mode on your gen1 then the gen2 will give you Adaptive which is a big improvement (especially so if you wear them outdoors or around other people). Same improvement that the AirPods had, if you’re familiar with that.

If you use them for videoconferencing, the lower latency and higher quality headset codec may be worth upgrading. They retain value on the used market so long as you unpair them from Find My an hour before you sell them and have a purchase receipt.

I suspect there might be some slight power savings for your transmitting devices if both sides support Bluetooth 5.3, but I would not expect that to be significant or advertised.