I’m not sure if it’s the “best” but I bought this and like two of my normal pillows new and have been THRILLED: PharMeDoc Pregnancy Pillow,... https://www.amazon.com/dp/B07WHSQ1SF?ref=ppx_pop_mob_ap_share

I’m a huge stomach and side sleeper and at a week post op it’s basically the only thing that 1) keeps me somewhat on my back (I cheat a little with an extra pillow on half my back to make it “feel” like I’m on a side without actually being on a side), 2) is comfortable to use in both my bed and on the couch, and 3) with the combo of my normal pillow and this, kept me where I needed to be and given me flexibility to sit up/down the most

Edited for another point and spelling typos from phone