We have to select a server at start of the game , the closest servers to my hometown is Europe, but now I'm in Asia for a long time but not forever , what should I choose? And it's will effect my ping? , or we can transfer our date from server to another in the future?
What you will do in my case ?

Fidstell
I say u should stick to EU server, even if the ping is a bit worse rn, its still better to endure a bit of rough ping on the start then having to endure a bit of rough ping for the rest of ur life after u get back home
Pyxios
think about what language you want to use in game. English? stay on America or Europe. asian languages? then Asia.
ES
I played Genshin on America, Asia and EU servers and didn’t get that much issue although my ping was RED for America server (200ms to 300+ ms) and YELLOW for the other two (125ms to 150+ ms).
I think you should be fine even if you choose EU because the yellow/medium signal strength status won’t be permanent if you’re going back to EU region soon.
VedXD
Can't transfer data between servers. So choose according to where you are going to be living permanently or play in both server. 🤔
Moran
Actually it will not significantly effect your ping if your wifi is good. I live in Asia(SEA btw) and I have some America accounts in genshin and hsr as well, however the ping is not very high. But if u want to stick with this game for more than 1,2 years, EU sv is better