Good catch, I do actually also like row 18, depending on flight duration I prefer rows 18-21 A or K (usually K), on shorter flights (DXB > India) I sometimes will take C or H, but then prefer row 20 (21 gets a lot of traffic bumping into you from the lav as it hangs a bit into the aisle as the lav aisle is wider. Also I found on some 77Ws row 21 doesn't recline, which surprised me as I've always had a reclining 21 previously.