Where are your friends going? which place has better teaching? which school is closer? do they both offer your choices? if you go to a worse school are you prepared to put that extra work in? How has your experience at your old school Been? All good questions to consider
I'm in year 13 now and last year when I was in year 11 changed to a school with better results. There's been some good outcomes - better grades & teaching, new friends, more freedom since it was a sixth form college. But at the same time cons e.g left my old friends, made a few annnoyingly fake friends, school is an hour away vs 15 minutes in my old school, stress from pressures of a 'good school' etc. but all in all I'm glad I changed to my new school. Also helped I despised my old school. But experiences are different, ik people who hated the change.
ultimately it's your decision and it's only 2 years and they will go really fast. Also you can always switch schools if your old school is nice enough after trying out the newer one.