To avoid bra lines, look for a bra with a higher back strap platform, which is where the strap joins the fabric. This will smooth out the fleshy part under the underarm and also allows for more coverage of the actual back.
Also, find bras with non-dig edges; for example, a raw-cut edge that lays seamlessly with your skin. Super strong elastics dig in where those bra edges end — you definitely want to avoid any tight elastic bands.
Shop Honeylove Bras
CrossOver Bra Wireless Bra
Honeylove's criss-cross mesh adds a signature touch, and a bonded underbust lifts without underwire. A wide wing with back-smoothing fabric eliminates back bulges. Adjustable straps and back let you modify your fit, and the straps can also be crisscrossed to stay hidden under racerback tank tops.
3D printed velvet adds support, and a bonded underbust lifts without underwire. Adjustable straps and back closure let you modify your fit. Straps can also be crisscrossed to stay hidden under racerback tank tops.