I build scan tools for shops and the best "all around" scanner that people seem to be going with is the BAUM DS2021... it's fabulous with Actual Values, control module replacing (coding transfer functions) and if you get the fully loaded one it comes with all the specialty connectors for all the pre obd2 vehicles. Also it has great coverage for BMW / MERCEDES / PORSCHE / AUDI that other scanners lack.
I actually have one, that I'm going to post on the for sale section if i find it. They normaly sell for about 5500 fully loaded with one year free upgrades.. The one I have is about 6 months old, fully loaded in like new condition and I'm looking for about 2700 for it. and the remaining 6 months of upgrades transfers to the buyer as well.