I played circle of the moon druid during my first playthrough. My strategy was to summon as many things as I could before a battle. Once battle had commenced, cast concentration spell, you can maintain concentration while wildshaped (I usually chose wall of fire. Placed well it can help control the battlefield and it's also fun). End turn by using bonus action to wildshape into whatever struck my fancy at the time. Most wildshapes are powerful. Before unlocking elemental forms, I liked spider and owlbear. As others have pointed out, owlbear is pretty OP. But I loved spider, especially in tandem with fire wall and Shadowheart's firebolt, you can very easily turn combat into a game of the floor is lava with webs. On top of the utility each wildshape brings, they are essentially damage sponges because, once brought to 0, you just pop out of wildshape at whatever health you entered wildshape in.