I have to admit I've only ever seen Lake Como from the air & know it's a long thin lake surrounded by mountains. Lake Garda is a much wider expanse of water comparatively & a far larger lake not surrounded by such a stupendous Alpine vista however very beautiful in its own right. The further south in the lake you go the less mountaineous the scenery becomes. I believe it is considered the most Italian of the 3 lakes being further away from the influence of Switzerland. It is dominated at the north of the lake by the Dolomites. The resort here where I stayed is called Riva del Garda which I would recommend. A trip into the dolomites can be taken easily from there including a trip to a nice restaurant to dine among the mountain scenery. From nearby Limone you can hire a speedboat to take out on the lake. From nearby Malcesine, on the opposite side of the lake, you can take a cable car up Mount Baldo & do some hillwalking. You can also visit Malcesine Castle there.
It is worth taking a tour around Lake Garda visiting all the towns & villages. Lake Garda is good for shopping with loads of markets. Check out this link.
Sirmione, stuck out on a peninsula jutting into the lake, is also worth a stop off on the southern shore of the lake with its castle spa & great views.
Here's a great link with links to the other towns on the lake.
Lake Garda is also a good base to visit Verona & Venice. almost 8 years ago