Hold or Replace?

I’m facing a tough call here. Rock Solid Heat Controller Conquest 90 now 18 years old. Ate an igniter early on and since then bulletproof. Inducer motor gets a bit noisy in fall for first day on start up and, after that, purrs like a kitten all winter. AC is 30 year old Lenox HS 18-261, but gets run 15-25 days a year so in some ways much, much “younger”. Say this is your house. Replace the system or hold on for now? I can afford to go either way financially.

source https://hvac-talk.com/vbb/threads/2228225-Hold-or-Replace?goto=newpost