I know people don't like to hear this, but there are a limited number of putters that are worth using as a main putt/approach disc and some are objectively better than others. Generally, stable, but not too stable (I'm looking at you, Rhyno), beaded putters will be the most reliable for putting, approaching and driving. The Warlock is one of the few exceptions that seems to be a reliable, stable putter that doesn't have a bead. The farther out you get and the more wind you see will both show the differences and usually, shortcomings of putt and approach discs. You can use other discs, but you'll be sacrificing reliability and many times useable driving distance.
The Wizard, Big Bead Aviar and Challenger would be the top three. I might have to put the Warlock in that category since it seems to fly just like a Wizard to me. Just below them I'd probably rate the Aviar P & A, Magnet, Omega and Voodoo. Maybe the APX as well. Where you rate them inside those categories is a matter of preference.Safe to say if you top five'd it, the list would be?:
Wizard
Aviar
Challenger
Rhyno
Warlock?
It's by no means definitive. I left out some disc like the Daredevil Beaver just because the companies are so small no one has really thrown them. But if you wanted a conservative pick for a good putter, you would have to go with one of those nine discs.