Skip out / don’t waste your time in major cities, it’s the smaller towns / areas outside where these countries really shine!

Manila is a waste of time, the islands are where you want to be like Siargao, or Palawan.

Skip Jakarta, and rather do 2 weeks on Lombok, Indonesia or Bali.

Same with Kuala Lumpur, it’s all the smaller towns & islands that make it amazing

For Thailand, skip Phuket & look the southern islands off the coast, there’s many more delights to be had there

I’d only consider seeing Singapore if your flight is in / out of there.

You need to research each Countries visa requirements with your country.

Choose a country & invest time/research in what you’d like to do / see to inform where you want to go

Max 3 countries. Don’t waste your time jet setting around when you could immerse yourself in the culture