I've recently discovered this beauty on Chaturbate that goes by Orimoreti. She has great reactions throughout her streams, but especially when she comes. Just expressions of sheer joy and playfulness. Sometimes she'll continue stroking to a second orgasm, where she gets more reserved and serious (which is hot because of the contrast to her first orgasm's reaction).
And an honorable mention to Sexxymichel. Her reactions aren't normally noteworthy, imo, but this particular clip of hers really stood out for me. Just the simplistic and raw grunting she makes during her orgasm is so hot.