FWIW, I recently flew UA's business from SCL - MIA (complementary upgrade), and ORD - MUC on LH's business. I really expected LH to outshine UA, based on previous trips, albeit in steerage. I found that UA's seats on the 777 were more comfortable than LH's 340, although that may be a little unfair, since UA just put in new seats. What really surprised me was the difference in the meals. On UA I had a very good steak dinner, whereas LH offered a barely passable mystery-fish entree. The staff on both flights were very attentive, without going overboard.

All in all, based on those two flights, I'd pick UA for a business class ticket, but YMMV.