Which are the good airlines to travel from Siem Reap (Cambodia) to Vientiane in Laos? Also, best airlines for travel between Siem Reap (Cambodia) and Thailand. Thanks in advance.

My first choice would always be Air Asia which I think fly all of those routes direct with the possible exception of Siem Reap to Vientiane. Where I don’t think you will find direct flights. You would need to connect somewhere using Lao , Vietnam , Thai through Saigon , or Bangkok or Phnom Penh. It may be worth looking at Luang Prabang as an alternative.

Thanks a lot for prompt response.