Best MacBook to buy for college and work

I currently have a MacBook Pro mid-2012 version, with 500 GB SATA memory and i5 5.2 GHz. After using it for 4 years, my system works well (there are occasional lags), but my trackpad does not work at all (I can get that repaired for $100). I am taking some Python classes right now, so I wanted to get a new MacBook. I am debating between a MacBook (256 GB SSD, 1.3 GHz i5) and a MacBook Pro (128 GB SSD, 2.5 GHz i5). I was wondering if 128 GB storage is quite small, as compared to 500 GB, and if the newer MacBooks have slower processing speed, so what aspect should I focus on as a student, especially for programming classes, and what will also be better for the long-term. I just want to get some guide on what would be the best laptop for me in the $1300 range. I could be misinterpreting this, but from the specifications of the newer laptops it looks to me as if Apple downgraded their products and made them weigh less.