I noticed that games in Company of Heroes are fought almost exclusively using infantry, with the addition of small anti-infantry armored vehicle (and the corresponding anti-vehicle guns). Bigger tanks often do not appear even late in the game (with the exception of game-breaking tanks like a Königstiger).
In my experience, serious tanks are too easily destroyed by a scouting opponent to justify their costs, so unless your secondary resources are outstandingly high I consider it better to stick to infantry and small vehicles.
Various replays verified this theory. In what situations do you really need to build tanks, and what are the advantages over a small-unit-strategy?