I'm lazy, so usually I'm using just infantry.
1. For defense, I'm using 10 CW - block with 5 infantry battalions.
2. For offence, I'm using 21 CW - 9 infantry battalions + 1 artillery battalion.
3. Against Germany, I'm using 27 CM - 9 infantry battalions + 3 artillery battalions.
4. I wrote this in another thread (but I cannot find it now, maybe it was in reddit), that I suppose that more soft attack and breakthough is a new META instead 20/40 divisions. So I like to boost it via doctrines - superior firepower - and support companies. This is in order, how I add it, when it is possible:
- engineers;
- anti-air;
- artillery (I like to change it for rocket artillery in mid - late game);
- flame tanks;
- tank reacon companies or logistic companies - it depends, previously I made logistic often, but lately I prefer tank reacon.
I don't know, if it is cost effective - I'm not a number guy - but it works cool for me and I'm enjoying the results
Usually I'm using CAS, but tactical bomber from time to time as well - it is good for generating more war score for example
Light tanks for flame tanks and reacon companies, I'm using medium tanks very, very rarely, heavy tanks probably never.