The original game has always been my favorite. The others got progressively less fun and more micro-manage-y, although if that's your thing, they're out there. With the original, Will Wright was pretty much just setting out to make a fun toy, not so much a realistic simulation -- the realism really came later.
P.S.: Most people are going to tell you Sim City 2000 is the best. It probably does have the best balance of simplicity and accuracy, if that's what you're looking for.