Marantz makes some pretty good integrateds, better than many of the non-japanese designs simply due to Marantz (like Yamaha, Sony, Luxman and Denon) knowing how to design a quiet circuit. I haven’t heard the Billie. It gets good reviews but I’ve seen quite a few of the mkII version on the pre-owned market already—unusual for what I imagine is a low-volume product.
For integrateds, I haven’t encountered any that outperform the Yamaha A-S2200 or A-S2100 for their street price. They combine the good traits of tubes and solid state better than any of the hybrid tube/SS products I’ve used/owned. Usually with the latter, instead of the “best of both worlds,” you instead get the worst of both.