Best Photoshop brush sets for painterly skies and gritty armor textures

[ScottYR]

I'm a digital painter working on a series of fantasy book cover illustrations, and I'm feeling limited by my current set of default Photoshop brushes. I'm looking for recommendations for high-quality, textured brushes that mimic traditional media like oil paint and charcoal, specifically for creating dynamic skies and detailed, gritty armor textures. I've downloaded a few free packs, but they often feel gimmicky or lack the control I need for professional work. What are your go-to brush sets for painterly, realistic effects?