Re: What would be best to run the latest version of Logic Pro, M1 iMac 4.5k 2021, or i7 iMac 5k 2020?
Hi D Rey -
The main consideration in choosing an interface will be i/o -- input & output channels. If you'll only ever be recording one of two tracks at a time then a small 2-in/2-out interface might be fine; but if you plan to record live ensembles, then you'd need at least an 8x8 interface [to start]. Interfaces can connect either via Thunderbolt or USB. Thunderbolt is good -- faster, but pricier -- but there are not as many options, and most are high-end; USB interfaces are plentiful -- just make sure you get one with the right USB version [USB 3 or 4 nowadays] and connector. I think most new Macs come with one or two USB-C connectors, which can handle both Thunderbolt and USB, but you'll need to do your due diligence and make sure you've got the right connections. [You may still need a USB hub if you have other peripherals as well [like a USB MIDI keyboard, printer, etc]..
MIDI controllers -- well that could be anything from one of those little 2-octave mini keyboards with pads -- for those who just need to tap out the occasional beat -- to full 88-note weighted keyboards for pianists and performing musicians; you'll have to decide what your needs will be there.
Generally, people who record mostly live instruments will have primarily audio tracks, while those who utilize synths and sampled instruments will have more virtual instrument tracks, which tend to be more CPU intensive -- I would assume the styles you mentioned would tend to rely a lot on virtual instruments.. But if you mostly stick to the virtual instruments included in Logic, they're not too CPU-heavy [and they're good], so you should be fine.
As to how many tracks you may use to build up an arrangement, well, that's going to depend on your own workflow. People who like to double things a lot and layer instruments and voices tend to have bigger arrangements with lots more tracks.
But unless you were doing something like full virtual orchestral mockups with tons of third-party instruments and effects I'm sure either of those Macs would be fine.