I don't understand why, but I've used rouned ones and toothed ones and the rouned ones slipped and the toothed ones are pretty much like having vertical dropouts, rock solid.
They shouldn't slip but they do. Anyway, the toothed ones still have very fine asjutemnt from tooth to tooth so that's not a problem, also you get a consistent wheel alignment unlike the rounded ones which is great as you don't have to re-setup your brakes.
All the cams are pretty much the same, i bought the Monty ones as they're were the cheapest, but don't forget the Monty bolts that come with the cams are a different size to the rest, but i guess you already have bolts so that shouldn't be a problem.