You can choose between American Megatrends and coreboot. They have a FAQ with the pros and cons[1]. But I have a hard time seeing why anyone would choose the proprietary American Megatrends firmware, especially since the laptop is targeted towards Linux users. Are they offering the choice for their older customers who are used to the American Megatrends UI? Or maybe to not anger the supplier (American Megatrends) that they've been working with for years?
I'm not well versed in UEFI firmware, but how is this possible:
> Due to how lightweight coreboot is, it will offer better performance and lower power consumption. For example, the LabTop Mk IV combined with coreboot will offer approximately 8% more performance and around 20% longer battery life (with a record of 13 hours and 42 minutes for general use).
I don't think I'd make that security tradeoff. From best to worst, I'd rank the options is this order:
(1) signed open source
(2) unsigned open source
(3) signed proprietary
(4) unsigned proprietary
In some cases I might rank #3 as the worst option if it prevents me from editing the firmware binary (to fix a security bug myself or to remove tracking info like a serial number), reverse engineering the firmware to verify it (because signed code is often encrypted as well), or installing alternate firmware that might be more secure.
[1] https://support.starlabs.systems/kb/faqs/ami-aptio-v-vs-core...