Not a "designer", but..
I might get beat down for saying this, but Im gonna say BananaRepublic, especially in recent years..True, they're not high-fashion, and true, it is very commercial and definitely in the mass-market category, but I havent bought anything that left me asking in disappointment, "I paid x-amount of dollars for THIS?" (which is more than I could say for some of the MJ pieces Ive bought in the past). Ive (only) purchased many solid-colored l/s t's, mainly for layering, and more "dress-up" items for my office-job days, and I havent had any problems w/ poor fabric that shrinks & fades (Gap?), or shoddy construction that renders the garment unwearable after, say, 3 wears (H&M?)...From what Ive seen, Ive always felt like I got what I paid for..