Congrats on both of your offers! This is more of a personal decision truthfully. Both companies (or any in the Big4 for that matter) are fantastic on your CV and give great experience. Even though the starting salary at EY may be slightly higher, all the Big4 companies bench their salaries against each other. They switch around and won’t be too different long term if you take in to account base/ benefits/ bonus etc. Both companies will offer you opportunities to work abroad (even though KPMG is for global services).
To make your decision have a look at the clients of each firm - who has the stronger client list and therefore opportunity for networking and experience. Also, have a think about culture fit from your application and interview process. Where did you feel most at home? Do you know any one from either firm? If so have a chat to them. People will more than likely be open to talking about their experiences so far and might give you some great insight!
I hope this helps. Good luck!