Like Roger Ray mentioned Korean Air is one option - but keep in mind that they fly only once or twice a week to KTM from ICN Korea. If you hop on over to SEA from YVR it may open up to more careers like Delta, Eva, United, Asiana which will bring you to East Asian hubs like BKK or HKG or Kul or SIN and from there you have either Nepal Airlines/Thai Airways/Dragon Air/Silk Air/Air Asia etc to bring you to KTM.
Now to your "reliability" question => Even with Chinese careers all I can say is look at their prior safety record. You can go to Wiki and get the safety record of just about any careers out there. But this is no guarantee for anything. Look what happened to Southwest at Laguardia yesterday. And as a pilot I will tell you that passengers can not possibly gauge into the safety-ness of an particular airline just from anecdotal data (at best) in forums like these.
As far comfort go - that's like opening whole different can of worms. Because of ever increasing competition, "sky high" fuel costs, and airlines not being able to charge the amount to bring in sustainable profit margins they offset it is by squeezing in more rows of seats/flight . And it is pretty much true worldwide with any careers. If the careers were to provide you ample leg room and reclining room all the capacity of the aircraft would be reduced to half and if we do a simple math - that would mean double the airfare which consumer are not willing to or can not afford to pay. Air cabins are not designed for people to be able to sleep - the cabin altitude is 8000 ft, with super dry air, the noise from the engines, turbulence, narrow upright seats - which is true with Boeing and Airbus no matter which equipment you fly. So they are designed far from people being able to sleep.
So for the most part air travel will always be an uncomfortable affair for the most people (at least when flying coach) for long distance for any foreseeable future.
Good Luck