There is no doubt that the front load models are the most efficient models and perform best in all tests. Less water is needed with the horizontal tubs. The clothes are tossed in and out of the water without filling the tub entirely. The top loading machines get your clothes clean but are gentler on your clothes which means that your clothes will last longer.
Even though the expense you will put out initially when you buy laundry machines is higher than you'd like, front loaders will save money on water usage as well as saving money on replacing worn out clothes.