For watercolor, you should try the bundle from @Pesi, it can be called a benchmark when it comes to watercolor:
You can also try those from @RamonM, you can not say those above are better, but they were always my first choice:
These are for stylus and mouse,
and these are optimized for mice.
For oil like paintings, you want to use the Memileo Impasto Brushes from @emilm, these are absolutely fantastic, but you better do not have a weak PC if you want to use them.
Another fantastic brush set comes from @Draneria, if you like metallic effects then you will love the Metallics by Draneria!
And you can find many other good and very good as well as fantastic brushes in our forums resource area for Brushes and Bundles.
Michelist