I've been running Sage Microsystems for about 15 years. I have 4 stores now. I like it alot. However, they just got bought out by DRB and their response on the service side has been suspect for a couple of months. I would go with Sage assuming they are able to right the ship on the service side, and DRB doesn't raise prices.... if not i'll be looking for new software myself in about a year. Auto Data would be one of the first ones I will look at.
15 years ago when I looked into changing from our old software (that isn't in the lube business anymore) the two big boys were Sage and ISI. We went with sage because it was windows based and utilized touch screens (easier to train old dogs on it).