Tektro Oryx seem to be notorious for not having the right leverage to really stop well.

The Tektro CR-720 brakes are inexpensive (less than $60 for front and back) and get great reviews. They are a "high-profile" brake so you would have to figure out if they would interfere with panniers or cause heel-strike problems. Those Paul brakes are probably as good as you can get but they are painfully expensive.