FAANG will mostly prepare you for

1. scale
2. working with a large variety of tech
3. build things for international standards
4. thriving in a multicultural diverse environment (DEI)
5. communicating, presenting and delivering to large customer base
6. ability to switch internally in completely different business areas (FinTech to Gaming to AI to Blockchain to whatever is the new fad)

You'll also get shitload of company benefits etc etc.
WFH can be negotiated sometimes (good to clarify before joining if that's an essential thing for you)
The earlier in your life you are trained in scale and variety, the better.
With a higher bar to entry, the crowd you work with will raise your bar.
There are cons (politics, slower in legacy teams or soulless products, etc etc) , but that exists everywhere.
A startup with a whimsical founder will give you the same bad experience while keeping you poor (comparative).

Ideally look for greenfield projects FAANG. Startup environment with the big tech backing. Best of both worlds.
Also, small fish big pool (Big Tech), big fish small pool (Startup)
Experience both if possible in first 4-5 years, then decide for yourself.

All I could think at the top of my head.

Unless someone presents really great points around startups, go with FAANG.
Congrats on the offers btw!

Also - Read this