Help in choosing MacBook Air M3 variant

Hi guys, I’m going to buy MacBook Air m3. Need to choose between 8gb with 512gb SSD or 16gb with 256gb SSD. Please share your suggestions who are using the same. I have a fix budget. Also, can you please share how much does it cost to take Microsoft apps subscriptions. PS: this will be be first MacBook and I’ll be using it for my MBA college. I want to use it for the next few years say 5yrs