Digital RCBS Chargemaster (I'd never go back to mechanical).
Starrett Digital Calipers for 6" and less, 24" Vernier caliper for anything longer than 6", a set of Mitutoyo Micrometers for things that require really really close measurements.
The nice thing about the digital calipers, is the ease at which you can compare lengths, by simply resetting zero. This item alone makes all the difference, saves time and reduces human error. Also, make sure your choice of digital caliper has the most important feature, automatic shut off to save your battery if you forget to turn it off.
AJ