It's cheaper to operate a 77W over a 346. Hence QR is also ditching their 346's for 77W's and EK/SQ never operated the 346 and went with 77W's. TG is choosing the 77W over 346 for their expansion as well and ordered 8 77W not too long ago.

They offer comparable capacity and range but lower operating costs.

IMHO I prefer the 77W over a 346 as well as it seems to be a quieter aircraft. Last week I did a segment on a SQ 77W and one on a TG 346, both overnights within 24 hours of each other, and I was surprised at the noise difference.