Hi aspirants

Both are good. In my point of view UPSC will be Better then ISRO.

As per my knowledge UPSC have more vacant then ISRO.  Any post in UPSC , it is more independent job, In ISRO, It will take years to reach to such independent level grade . If you want get transfer to some other palace , it is lest possible in ISRO. Salary is almost similar in both ISRO and UPSC

Hope this Helps

Good Luck!