Cisco suggests some images based on multiples factors such as: quality and stability, longevity and adoption rate.
They are marked in the download portal with a star.
Unfortunately there are no sugested versions for anyconnect.
To choose the best image for your environment you would need to read the release notes, bugs and security advisories.
You can also use the following tool to sort the images more easily:
https://software.cisco.com/selection/research.html#?mode=&tid=P&pid=&sid=&cr=&crt=&hid=&fid=&cp=
HTH
Bogdan
