I have owned a pool for about 15 years and it looks like i need to purchase my 3rd robot. My other robots have been dolphin. The first one had dual motors and lasted the longest and probably did the best job. The second one lasted only 4 years. I went to our local mom and pop pool store and they claim that dolphin parts are harder to come by and now only sell polaris. I bought the dual motor one on line and the 2nd cheaper single motor one from them. Looking online it appears most reviewers prefer the dolphin products. Any particular recommendations for the higher end series of products. I like it better if its a basket or bag then the cartridges personally.