How to best deal with cracks in concrete?
Replacement is the most expensive but best solution. Be sure the base is properly prepared and compacted, and use reenforcing steel, which I have to suspect the current installation either did not, or not nearly enough. Steel is very inexpensive in the overall cost of having concrete poured, but adds a huge amount of strength to the result.
It also seems doubtful that &quot;control joints&quot; (neat, tidy, straight grooves in the concrete to encourage any cracks that DO form to form &quot;just there&quot;) were made in the slab we are looking at. Those typically want to be no more than 12 feet / 4 meters apart.
Topping will soon crack in the same places, as the chunks of cracked concrete under it will continue to move relative to each other. Only if the topping was thick enough to sustain reenforcing steel of it's own might it hold up, and at that point you might as well go the sure route of replacement.
Sealing the cracks is a stopgap. Again, the chunks are now moving (slowly, for the most part, with the seasons) with respect to each other, so it's expected that the sealant will crack (if hard) or tear open (if flexible) eventually. On the other hand, as long as you can stand it, it's by far the least expensive solution.