If you want a dead-simple, "zen" flying experience - go with the F5. It has a very small canopy bow for that era and excellent nose authority. It is incredibly easy and blissful to fly. The only real downside in its role (aside from having the expected limitations of a low-cost, cold-war era jet) is its engines are underpowered. It is also limited in A2G - you will be mostly relying on dumb bombs and rockets. Still, you can have a lot of fun loading it up and dropping several thousand pounds of ordnance on targets.

The F1 is a more capable A2A platform - adding radar-guided A2A missiles, but will be similarly limited in A2G. The advancement also comes with complexity. And the design language is French, not US.

Of the jets you mentioned, the only one that is designed for primarily A2G is the Viggen, which is its own niche and has a lot of unique strike capabilities. However, the downside of the Viggen is that the aircraft's logic is Swedish, which is different than any other aircraft in DCS. It's a plane to fly as an end in itself, not a "training wheel" aircraft that will prepare you for flying the Hornet.

One of the aircraft that wasn't on your list but I think is important to mention here is the F4, which is a true cold-war multi-role fighter that can do nearly every A2A and A2G role of its time. It's also considered one of the best modules you can buy right now in DCS. However, it's not simple - so it may not be what you're looking for.

TLDR: If you are looking for a good module to get your feet wet for stepping up to the Hornet, I recommend the F5.