Picking itinerary in SEAsia as an exchange student in HK

I’ll be an exchange student in Hong Kong this coming september and I want to use this as an opportunity to travel around neighboring countries. I’d like to go to about 3-5 destinations depending on how much time I have, but I’m having a hard time deciding where to go. I have a budget of roughly 2000 euros for all trips this includes flights and accommodation. My biggest factors are safety, cost of living, visa restrictions as a French citizen, and activities in general seeing as I probably won’t stay anywhere longer than 3 nights I want to make the most. So far I’m set on going to Bangkok, but I was thing of other places like Vietnam, the Philippines, Taiwan, etc. It’ll be my very first time in Asia and I don’t know when I’ll come again which is why I really want to travel and discover as much as I can. Which countries would you recommend? Also any other tips in regard to traveling around south east Asia are welcome.