2.2 GHz Intel Core i7, Turbo Boost to 4.0 GHz (Crystalwell)
16GB 1600 MHz DDR3L RAM
256GB PCIe-Based Flash Storage
Integrated Intel Iris Pro Graphics
15.4" LED-Backlit IPS Retina Display
2880 x 1800 Native Resolution
Thunderbolt 2, USB 3.0, HDMI
Force Touch Trackpad
2.9GHz quad-core Intel Core i7, Turbo Boost up to 3.8GHz
16GB of 2133MHz LPDDR3 RAM
256GB PCIe-based onboard SSD
Integrated Intel HD Graphics 530
15.4-inch (diagonal) LED-backlit display with IPS technology
Force Touch Trackpad?
Four Thunderbolt 3 (USB-C)
Radeon Pro 460 with 4GB of GDDR5 memory
3. Touch Bar
If you can live without the fancy new touch bar until prices drop, go with last year's model.
4. Future Proof
If you go with a maxed out model from 2015 it will likely be able to keep up with the newer machines for at least 2 years.
5. Hate USB-C
If you hate USB-C, go with the 2015 model.
Thanks for reading, and if you have any additional input leave it in the comment below.