Well, the first book that always leaps to mind for me is 'The Mortal Instruments' series, especially the early ones like 'City of Bones'. It's not solely about angels, obviously, but the Shadowhunters being Nephilim puts angelic lore and the conflict with demons right at the heart of it. The battles can get pretty cinematic, with seraph blades lighting up and all that. It leans more urban fantasy, so the heavenly warfare is often grounded in a modern cityscape, which has its own appeal.
If you want something denser and more mythic, you could try 'The Divine Cities' trilogy by Robert Jackson Bennett. It's not angels in the classic winged sense, but it deals with gods and the fallout of their battles in a way that feels like a cosmic, post-heavenly-war drama. The scale is immense. Honestly, for pure, unadulterated angel-on-angel (or angel-on-demon) warfare, I often find myself going back to comic books or manga like 'Angel Sanctuary', though the tone there is wildly melodramatic.
A lot of the angel fiction I've tried gets bogged down in romance subplots, which isn't a bad thing if that's your jam, but it can dilute the battle focus. I remember starting 'Angelfall' by Susan Ee and enjoying its post-apocalyptic take, but it's been years.