What you pick for brigades should mesh with your overall style of strategy/play. Also, Cost effectiveness in terms of ic and manpower are huge factors, the terrain, and the metagame are things to consider when choosing what to put on your divisions. I personally go with Art+Eng, because I love playing Germany and the Soviet Union. It's a good balance of power and speed. There are alot of rivers in Europe and the terrain makes a mobility focused strat very effective. If you wanna pick a defensive strat and can afford to not care about speed, like in mountainous or low infa provinces, then stacking medium or Super-Heavy armour might be a good. Lol, there are so many factors to consider, but exterminating and learning what's worth using is so much fun. I would NEVER, ever, use naked divisions, or inf with one Brigade. The stacking penalty for divisions is very potent and should always be avoided. If you overstack, your advances have a high chance of failure. You'll be wasting manpower, Organization, resources and time. The next patch is going to increase the stacking penalty, so be sure to have every div. with max brigades. So avoid a inf div. spam strat. cuz it's getting nerfed and it's kinda for noobs.