I'm not sure you can find anybody other than John Barsness who has both and can compare them. I have the Hornady and like it for many reasons: the one-page instruction sheet, the unit's small footprint on my bench, and the three dispensing "speeds" (actually just changes in the time it changes from fast dispense to trickle, by weight).
If you check prices, you might be drawn to the Smart Reloader ISP. I wouldn't advise it. Its instructions are gibberish, it has to be re-programmed for every powder and charge to optimize dispense speed (or be horribly slow at the default settings), and it takes up a lot of room on the bench with its "warthog's face" styling.
I think you'd be delighted with either the Hornady or the RCBS.
