Whirlpool WTW6400SW Top Load Washer

We've had this machine for about 18 months and have been disappointed with its cleaning ability from the start. We have 2 active boys--dirt, grass stains and basic food stains are a trial to try to remove and most often don't succeed. I have attempted to remove dirt stains by washing 4 times, pretreating each time, presoaking by hand one time, applying bleach directly another time, and using the pre-soak and heavy duty options each time to no avail and that baseball uniform still looked as if it hadn't been washed. The service man was out and said the machine works as it was designed which he acknowledged was not very good. I guess the wrinkling of clothes is an issue as well but honestly I haven't focused on that because its cleaning ability, which is my main need in a washer, is so pathetic, or as my husband would say "crappy." And now my question is what machine to replace it with? If I looked at the totality of reviews on this machine I might think it was good too!