Which UEFI vendors care — or at least may care — about security? The list (alphabetically) is shorter than you might expect:
AMD
AMI
Apple
Dell
Hewlett Packard Enterprises
HP Inc.
Insyde Software
Intel Corp.
Lenovo
Microsoft
Phoenix Technologies
Nobody else. If your vendor is not listed above, ask them why you should purchase a UEFI-based system from them.
The above list is from the list of vendors who have feedback mechanisms listed on the UEFI Forum’s security contact page.