We used Nepal airline.
They have an office in Ktm.
We were there out of season so only booked a week in advance.
The standard rate is140 usd we only paid 120 however we soon found out why when we
Boarded the plane.
It was a cargo plane and we were the only two passengers,
But hey honee got there a
Safe and sound
We flew with Tara Air 4yrs ago from KTM to Lukla and it was absolutely fine. Don't know if it's still the case but at the time Tara Air and Sita Air seemed to have a bit of a duopoly going on since I don't recall seeing many if any other planes up there. Suspect the providers are much of a muchness to be honest.