Hot Water Heaters

[Holladay]

(an aside, 4 people in the house and 2 of which are teenagers) I have 2x50 gal propane hot water heaters, 10 years old, set up in line. The thought was that have one (the last in line) fairly hot, and the first just warm. When the needed, I could turn up the first to hot as well...ie when I wanted to fill the big bath tub.

The first in line has stopped working. I can't /won't light. So we have been working on just one. Which is OK because we have the other (last in line) that works fine.

I am looking at upgrading the tanks. I saw online to have 1 propane tank coupled with a "tankless" hot water source. I don't know the price, setup requirements, cost etc.

I just want to have adequate hot water. Again, have two teenagers and a big bath tub that we don't use that much.

Should I just replace both 50 gal propane tanks, have a repairman come out to fix the first in line that doesn't work, or do the hybrid propane tank and a tankless source?

Cost is an issue to a degree. Or the increased value to the house with a tankless?

Thanks