1) If you were to recommend a platform which one and why.
1. You can check the platforms in this coin market cap list. At least, you can check and evaluate which is best for you depending on your needs, living, and also availability. Number 1 is the top platform based on the CMC list and so on others.
https://coinmarketcap.com/rankings/exchanges/But once more, analyze which is available to your country because sometimes, some platforms are not available in your country. Never use the non-reputable exchanges, new exchanges, or exchanges with more negative reviews.
2) If I was to stake my 1 bit coin what would I get in return as a passive income.
It will depend on what platform you are investing in. Because you are going to invest that 1 BTC that is considered a big amount, you must stake it on the trusted platform. Never only be interested in high rewards, because sometimes, there are scam exchanges or platforms that offer staking reward with high return.