The strongest solvent is surprisingly water.
Water is considered to be the strongest solvent because water is actually capable of dissolving more substances than any other liquid.
Water is important to every living thing on earth including humans.
So wherever water goes, either through the ground, through our bodies or through the air, the water takes along with it valuable chemicals, minerals and nutrients.
For chemical solvents other than water, the strongest chemical solvent is considered to be Fluoroantimonic acid.
Liquid ammonia is also excellent for very strong reducing agents.
Other strongest chemical solvents and solvents are dimethylsulfoxide and hexamethylphosphoramide.
MEK or Methyl Ethyl Ketone and Acetone are also pretty strong solvents, although Methyl Ethyl Ketone is a stronger solvent than acetone is.
MEK or Methyl Ethyl Ketone is stronger than Acetone, because Methyl Ethyl ketone has a slower evaporation rate and boils at a higher temperature than acetone does.
These differences are why MEK can be a stronger cleaning agent than acetone.