You don't need to go on COBRA and exhaust its benefits before signing up with the ACA. IMHO, the only reason you would want to sign up for COBRA is if you or a family member are undergoing care at a hospital and you don't want the continuity of that care interrupted.

The ACA is going to be far less expensive than COBRA . If you are on COBRA and the company declares bankruptcy, you lose COBRA and must sign up for the ACA.

COBRA is not a realistic option for most people. Without the employer contribution, most health plans end up costing more than $1k/mo. That's too much for a steadily-employed person to afford, let alone someone who was just laid off.