It's nigh-impossible to compared a hitter to a pitcher. Both have considerable injury risk, Berrios just for being a pitcher. If Buxton can hit for power, that cancels some of the loss of speed he'll inevitably suffer. The real question is if Buxton can stay healthy now that he's a bit older. If so, and if forced to choose, I'd say Buxton. Given their track records, Berrios is set up better for a long-term deal at the moment though. Maybe Buxton with a buyout option in the middle?