Total suffers the same vulnerability as ACI - mainly they are part of a larger organization and would be adversely affected if a ransomware attack succeeded with the parent company. Corelogic and their owners would be prime candidates.
SFREP, Clickforms (Bradford), Total, and Homputer have all been around for some nigh 30 years if not over. But I suspect Clickforms and SFREP as well as HomPuter would be the least likely to come under an attack like ACI. Total is by far the largest and perhaps most complex of the programs but I would vote for Clickforms and the easiest to learn. I've not tried SFREP since they bought out Wilson. I'd try then first though as they have a six month free subscription to new people.
Look in the tech forum and see who has the least complicated problems to solve from users. HomPuter is not there and NCV is gone after the suicide of the owner (who was basically sued out of existence by Bradford.)
Like any basically on line program, all are vulnerable to attacks and outages.