I'm listing pros(+) n cons(-) of each
Asus R510JX:
+Best CPU (quad core i7) & GPU (GTX950M) for the price
-Average battery life
-4GB RAM soldered in board, only 1 additional RAM slot which already has a 4GB RAM (max RAM 12GB possible)
HP au
+Slim & light
-ULV CPU, average GPU
HP ab523
+Cheaper than competition
-ULV CPU, average GPU
I'll recommend Asus, if battery life & a bit bulkiness isn't a problem. You can play new games too.
For college works you don't need a high performance laptop. If you are not so into gaming, you can save money & buy HP ab 205TX for 50k (Add a 8GB RAM & SSD maybe for better performance in day to day tasks) [I've mentioned it earlier too]
Asus has a back to college offer too
Register | ASUS Back To School Offe