The tear out near the sink cutout is the blade's fault, not the wood's. Poplar gets a bad name because guys run a 40 tooth combo blade through it and then blame the species when it fuzzes. A sharp 80 tooth or even a zero clearance insert and that cutout comes out clean every time. Eating $60 on birch for a box that's getting painted is money down the drain, and birch has its own issues, it chips out just as bad if you look at it wrong. You made the right call, you just need to fix your cut, not your material.