From a practical standpoint, the RCBS ChargeMaster Combo is the choice. It eliminates both a mechanical scale and a mechanical powder measure. However, its 300+ price tag may be prohibitive. Here's a nice discussion:
RCBS's ChargeMaster. - 24hourcampfire
The ChargeMaster's process can be accelerated by manually adding powder to the pan while it is discharging.
The better mechanical scales are made by Ohaus and are marketed by Dillon and RCBS (502, 505 and 10-10). Redding's scale is also excellent. The 505 scale, which is featured in RCBS's RC kit, is three-poise; all of the others mentioned are two-poise. Some like complexity, others simplicity.