<p>I have also only visited Oxford. You may have felt that Oxford is a “little big” city. During term time, you’ll most likely not leave the city, but you have the option to go to London if needed. In the case of Yale, you will be based in a much larger city surrounded by even larger cities! </p>
<p>I’m sure you are probably aware of the following this, but I think you should continue to bear them in mind when making your decision. </p>
<p>(1) When studying at Oxford, you will take (almost) no outside courses – every one single of your courses will be chemistry. At Yale, though, you have can take many outside courses and you have the option to switch “major” if you want (not at Oxford).
(2) At Oxford, students are strongly advised not to take any employment or extensive extracurriculars, because the course is rigorous from day 1. At Yale, employment and ECs are encouraged. In fact, many students say that they felt pressured to join them.
(3) At Oxford, you’ll need to pay tuition, college fees, accommodation, etc. For EU/EEA  students costs can often get upto £20,000 p.a.  Yale, however, includes all of those as part of your FA package.</p>