With that range of vehicles you might want to just jump in and get a pro quality machine and learn to use it, Newer vehicles are just getting worse when it comes to electronics and even need a tool to do oil resets, brakes and other more routine things. My latest scan tool is a ThinkCar Thinktool Pro S and it is a true pro level tool (basically the same software as a Launch but less money.
To see one in use take a look at some of Ivans videos here is an Amazon link as well. Now if you don't mind having a smaller screen and losing a few of the higher level functions you could opt for the Thinktool Pro
Or look at some of the Launch line.