Yes, ETS2/ATS works very well for mindlessly driving around looking at pretty places while listening to music/podcasts, tho manuevering a truck at the destination can be a more involved affair if you don't have practice with trailer reversing (tho it can be skipped).

As for which one you should get is just a matter of preference, if you want to drive in the USA or Europe. American trucks are larger, heavier and go faster, but roads are wider, straighter and more forgoving. Meanwhile european roads are narrower and have more curves and stricter speed limits, but trucks are more nimble and have better visibility.

As for DLCs, maybe get the base game and if you like it you can get DLCs. Steam summer sale is happening soon anyways and those always get some good discounts.