This is not a definitive answer.
The solvent closest to water in its properties such as dielectric constant, melting/boiling points, etc are formamide and sulphuric acid.
F S W
Melting point (⁰C) 2 10 0
Boiling point (⁰C) 210 337 100
Dielectric Const 109 84–100 80
Specific gravity 1.133 1.94 1
But water is the simplest i.e made up of only two types of atoms (Which are decently abundant).
Regarding silicon: even though silicon can undergo some level of catenation (silanes) it is not comparable to carbon. Silicon can form polymers like silicone (poly-siloxanes). But I think carbon seems to be more versatile. It is also more abundant (check this out. A nice representation of abundance of different elements in the universe)
Also check this out: it is about exoplanet habitability.
Since certain elements are more abundant than others, the likelihood of them giving rise to life is higher. Therefore water seemingly emerges as the life solvent.
[still most times we see everything in an earth point of view]