There are none to be avoided, and no best years. It simply boils down to buying the car with the spec you want, in the colour you want, with a proper service history and provenance. I love the manual and have had three (totalling over 100,000 miles and never needing a clutch). But others (especially townies) prefer the auto. Just work out what you want and buy the best in your budget.
Overall, as long as you buy from a reputable specialist (or get a proper pre-purchase inspection), you'll be fine.
My recommendation is that you call Richard Grace Cars, give Dicky your budget, wait, and let him come up trumps.