It will be useful to know which specific programmes you are choosing between, but it's completely understandable if you'd rather not share. Overall, the MPhil is a better degree title for if you want to go into further research, and the MSc is more well-understood (and you won't face the issue of people assuming you dropped out of a PhD)
Additionally, which colleges were you allocated to for each university? This can play a significant factor. For instance, in terms of overall finances, if you have an offer for a very wealthy college in Cambridge as opposed to a less wealthy one in Oxford, you'll find that you'll have more opportunities overall to get grants/bursaries at Cam rather than at Ox (and vice versa of course)