Did you install Coreboot?

I have QubesOS installed on my laptop. Is it a good idea to install Coreboot to make my laptop more secure? Is QubeOS enough?
If I install Coreboot, which do you think is better - Skulls?Heads?Regular Coreboot?

I installed regular Coreboot on my X220. The internet has plenty of guides on how to do that.

Yes, if your laptop is supported by the coreboot software, it is a good idea. Intel Management Engine is a devil.

Coreboot doesn’t remove ME, and it doesn’t give you any options to disable or clean ME you wouldn’t have with the stock firmware.

Coreboot doesn’t but the me_cleaner does. The guides on the net generally combine me_cleaner with coreboot install on Thinkpads.

Some guides do, the recommended way to install coreboot is to only replace the bios region, which leaves ME and GBE intact.