I wouldn't recommend Laos. They scrutinize documents and particularly your Financials a lot more than others. For starters, you'll need a 6 month statement with at least 3 months work of 500K banked. If you have less than 3 months of 500,000 Baht in your account you won't be getting your visa except with the help of an agent, which charges
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Baht. For that money you might as well fly business class to Ho Chi Minh and get your visa there.
Vientiane does take only 3 days and 2 nights to issue your visa. Same as Ho Chi Minh, but they're moving to the e visa system soon (Cambodia also).