i make a lot of my own brushes, simply by playing around with the settings.
these are some of my favourite "base" brushes, that are great on their own or that i just use as is.
T-marker 
watercolor/copic feel, because you can build up the color
Intoxicate Pencil Set
my go too shade/blush details, also makes a great eraser for more sketchy pieces
Su-Cream Pencil
Pen (ぺんペン)
Ma's Pen
softcore
Tiger Brush
i've played around with this one the most for the Roadkill Asylum art.
YOTTI PEN
feels a lot like the paint tool sai pixel pen/brushes
Ink's Too Dry
this is also a heavily edited brush for the Somnium Saturnia comic lineart
Hoarse Watercolor
Grunge Dot
Used in my Fruit Girl Fashion and the Somnium Saturnia Bedtime Pinups
Neon Pen
Used in my Season Witches and the Somnium Saturnia Bedtime Pinups
Qamala's Graphic Marker
things like textures, stamps and decorations
Space Brushes
Stars
Leaf Brushes
Body Hair set
Bistecchia's Body Hair
Tree Brush
Hand-Painted Casual Deco
Various star brushes
Chains
Lovely braid pen
Distant Leaves
these cost clippy points. i basically hoard mine for as long as i can from login events, but i guess you can earn them in otherways too. there's more info on the clipstudio website
Nuta Marker
a lot like the T-marker, but feels more thicker, than textured. looks a lot like Ryoko Kui's Daydream Hour sketches/illustrations
Scattered blood
another heavily edited one i use alot in Roadkill Asylum
Hair Highlights
Watercolor Weeds
Pine Tree
Hospital ♰ Sticker
A chain with a little bit of line
Pen + pencil
Glitch Brushes 3
Natural Landscape Brush Set
Y2paint built in blur
fox tail
Starry sky brush