I have a machine very similar to your option 2. Mine is a 2017 iMac 5k with the 8GB video memory, the 3.8 Ghz i5, and the 3TB fusion drive. Personally, I like the simplicity of a larger internal drive so I don't have to worry about having a bunch of external drives connected to my machine. I find the fusion drive to be a good compromise of speed and size.
In an ideal world, I'd only have SSDs, but that's fairly expensive for all the space I'm using (currently about 1.5TB). Having only a SSD will be faster than the fusion drive but a fusion drive with a 128GB SSD + 2TB HD, will seem a lot faster than your existing Windows PC or a HD-only Mac.
You know your workflow better than anyone. How hard will it be to live with 500GB of storage for the 4+ years you'll be using this iMac? I would guess option 2 would work better for you.
By the way, your option 2 is available in the Apple Refurb store for $1950. I've owned a few refurb Macs and have had good luck. You could use the savings to buy Apple Care to get 3 years of warranty and still save money (
AppleCare+ is $170 I think).
https://forums.imore.com/e?link=http...token=jcrazj_S
The available stock in the refurb store changes all the time, so if you're looking for a specific config, check every day until you find it.