Are inflatable or foam backpacking pillows better?

It depends on priorities. Inflatable pillows (like the Sea to Summit Aeros line) pack down to almost nothing and weigh the least, which is why ultralight-focused buyers favor them. Foam and hybrid pillows (Klymit Drift, Nemo Fillo) feel more like a pillow from home and are quieter and warmer against the face, but they're bulkier and heavier. Side sleepers and car campers tend to prefer foam or hybrid; gram-counters prefer pure air.