Gadol, not being an expert, I googled rankings of supremes by experts. From several samplings, Gorsuch and Kagan head the list. Thomas occupies between 3 to 5. Sotomayor between 6 and 8.
While both are at the end of ideological spectrum, Sonya is also more ideological (score -4), Thomas 3 (next are Alito 2.2, Breyer -1.9, Kagan -1.5). That is Thomas is 0.8 away from the next, while Sonya is 1.0 more from Thomas.