I've been a loyal customer of Mike's for several years now. I started going there because of some coupons I got in the mail. I've kept going because of how nice and fair they are.
Their warranties are good. I've only had one time where a part stopped working. They replaced the part for free (of course, it's under warranty) and did not charge me any labor to replace it.
They've done lots of work for me and have given me some great deals because of my loyalty.
They are helpful. They explain any problems or conditions and tell me what they would do and why.
Their prices are very fair and, when ordering a part, they always shop around for the best price.
Another great thing about them is their free shuttle service. This is very helpful when you are a family of 4 with one car. They will pick you up and drop you off...in Provo and Orem, at least. I'm not sure how far they'll go. This has been immensely helpful. They've even driven me from the shop to my son's school to pick him up from Kindergarten.