I am planning to buy 3s or 4s batteries, which one is better? skycell, lipos or any other? also 11.1v is good enough or should i consider 14.8v, if i plan to upgrade the motors?

You need to first determine the specs of your power train before lipo purchase. AUW .

3s1p, 11.1 v, lipo battery, 30c or more, should be good for 4 1000kv, 170w motors (load current 15.6 A at 11.1 v)

what i am asking is that should i invest in a higher volts battery, but in that case i will have to use a buck converter in case of 11.1v motors, and in future if i need to upgrade the motors i might use the same battery.

but that's not really important, i will just go with 3s battery, but i want to know which brand is good. i see a lot of brands in india like zop power, orange, skycell , and a lot of other brands.

As Vikrant said 30c battery will be enough. But I suggest you to go for a battery with higher discharge rate. Dont go for orange LiPos. I had one. Its not good enough.But considering the price range its okay. Try CNHL, ovonic, tattoo lipos. I have been using both tattoo and ovonic lipo using from last year. Its great

Orange lipo battery are not good

I am using Oranges for fixed wing for long. I have no problems with them.