Overall the new iMac with a Core i7 processor and Radeon 580 graphics is the fastest Mac available today. Only if you need to take advantage of parallel tasks or multiple GPUs should you consider a current Mac Pro.
Apple also unveiled a new iMac Pro at WWDC and has promised a redesigned Mac Pro so professional users may want to wait for those if they can.
Single-core performance increased by up to 9% when compared to the equivalent 2015 model, and by 20% when compared to the equivalent 2014 model.
Multi-core performance increased by up to 15% when compared to the equivalent 2015 model, and by 22% to 27% when compared to the equivalent 2014 model. The Core i7-7700K model currently has the highest single-core score and the third-highest multi-core score on the Geekbench Mac Benchmark Chart.
There isn’t much difference between the Core i5-7600K and the Core i5-7600 models. While the i5-7600 has a lower base frequency (3.5 GHz vs 3.8 GHz) it has a similar turbo frequency (4.1 GHz vs 4.2 GHz). For CPU-bound tasks there won’t be a noticeable difference between the two models.
GPU performance has improved considerably with an increase of up to 80% when compared to the equivalent 2015 model. Even the “low-end” Radeon Pro 570 in the 2017 model is faster than the “high-end” Radeon R9 M395X in the 2015 model.
Both the Radeon Pro 575 and the Radeon Pro 580 outperform the FirePro D700 found in the Mac Pro. Note that the Compute Benchmark only measures the performance of one GPU at a time, so tasks that can use multiple GPUs will still have an advantage on the Mac Pro.
You can download Geekbench from the link below...