I recently bought the E480 (20KNS0LE00) and would definitely vouch for it.

(converted INR to USD) The initial specs were ($730) - 4GB RAM - i5-8250U (8) @ 3.400GHz - 1 TB HDD

I decided to upgrade to 480GB SSD and 12GB RAM as it has two memory slots. The upgrade cost me $120

I am running arch linux on it and it's pretty smooth.

The only downsides are: Display is not FHD and the Keyboard is not backlit. (The models here in India do not seem to have them, but I really needed one as my current laptop was almost unusable.)

I select a Thinkpad with large RAM, large disk storage, high resolution, smallish physical screen, and as close as possible to selecting all-Intel peripheral chips for USB, video, sound, etc. This gives a laptop with huge longevity for minimal upgrade. Also get the largest battery option you can, but that can impact adversely on weight considerations.

Currently still using my ThinkPad T410S which has only had an upgrade to the HDD from 500gig to 2000gig in its nine-year lifetime. And one repair: a keyboard replacement when two arrow-keys stopped working. Though its screen resolution is now starting to feel a bit 'tight'.

A ThinkPad P1 has the most upgrade capacity, from my experience. I have max specs. Including a hexacore Xeon CPU, 4K screen, 64GB of RAM, and 4TB of storage.

i would go for the specs which cannot be upgraded (easily ) down the road: screen ( size and resolution ) and max RAM slots. After those, the fastest CPU available for the configuration.

The upcoming X1 Extreme Gen 2 is what I'd get. If you do Haskell, and venture into FRP land (reflex), then having 32GB of RAM is recommended.

(I own the P71)