According to Geekbench the iMac has the best single core performance of any Mac, and best multi core performance vs the MBP:

https://browser.primatelabs.com/mac-benchmarks

I really enjoy my 15 inch MacBook Pro (late 2016) despite not having dedicated fn keys and a few other issues. With the 4 Thunderbolt 3 ports I have attached a Razer Core with a GTX 1070 and can use my HTC Vive different places with little effort. Took a bit of hacking to get running however. Make sure you bump the fans, it seems apple wanted these things to fail quickly with normal unmodified temps of 80-90c... Mine runs at about 70c with the fans maxed doing VR.

could you provide details and instructions for how you got the razer core working with a mbp? thx!

I have the 2015 iMac maxed-out (32 GB RAM, 256 GB SSD, 4Ghz QC i7) as a desktop and I can't really compare the 5k, 27-inch screen experience with any laptop I can think of.

I am opposed to the Mac Pro it is not what I need.

Should I buy a fully-dressed iMac or MacBook Pro?

Mostly need CPU speed, not so interested in GPU speed.

multiple cores a plus

Comparing a laptop vs. a desktop? Which do you need? I've got no idea what your specifics are or whether you'll be permanently stationed at a desk or if you'll be working on the subway 24/7.. the current state of this post provides very little beneficial information for the HN community.

OP added more details two hours before your comment (https://news.ycombinator.com/item?id=14066852). It's about raw CPU speed, not form factor or mobility.