Water Heaters - Advice needed on otions while replacing 2 water heaters

I recently bought a home with 2 - 50 gallon electric hot water heaters. Both have a date of 1988 on their stickers. Both are showing rust around the bottom. There are 4 adults in my home and 2 children. My question is whether to replace these heaters with 2 more 50 gallon units or to put in 1 - 80 gallon unit. I have an apartment in the basement where my parents live so there's a second kitchen, laundry and yet another bath down there to consider. I figured I'd ask instead of guess. I figure at the very least a new unit/s will be more efficient.

TIA

It seems that water heaters tend to break at the worst time.
You are smart for thinking about it before they leak and cause a flood.

I would go with the two 50's. 100 gallons is not too much for 6 people. Besides, with 2 units you'll still have some hot water should one develop a problem and stop heating.