First world problem?
Anyway, if you are flying to HKG, the flight is flying to the south of Himalayas, so A seats. But (1) the Cathay Dragon flight isn't a scenic one but flies towards southeast to Dhaka after taking off in KTM, and (2) based on my experience (and also as many have said), the cabin is much brighter than outside at the time the flight is flying out of Nepal, your chance of seeing the Himalayas is quite minimal. You may roughly see some mountains/hills at best.