I have both devices at home , my personal device is the Thinkpad yoga 12 and my mother device is the Surface Pro 3 (I actually wanted to buy the Surface but could not afford the i7 version , so I got this i7 thinkpad yoga for 650$ last black friday)
after using both devices I can see advantages and disadvantages to each one :- Thinkpad : a truly great keyboard , easily used in lab while typing , disadavtage is it's weight , really it very hard to use as a tablet and write with pen on it (also the pen is not as good as the Surface pen , it's not accurate at corners and when tilted)
Surface: I never saw windows run so smoothly and with know issue as I saw with this device (it really show how awful are OEMs with there crapware ) , the weight is amazing for a computer , very usable as a tablet and when writing with the pen , the pen is very accurate even in corner or if tilted , the disadvantage is the keyboard , it's not a good typing feel (because it's too thin ) but this is solvable by not getting the type cover instead buy the Thinkpad bluetooth or wired keyboard + a bluetooth Arc mouse
Amazon.com: ThinkPad Compact USB Keyboard with TrackPoint - US English: Computers & Accessories
also consider waiting for Surface Pro 4 , it should be available last summer or early fall (maybe it get released before you start your next semester)
also the most important is use "Onenote" it's the greatest program for note-taking and studying