I think first you have to decide whether you want SS or Aluminized. And if SS which grade.
There are some great buys out there right now, Diamond Eye for one is a nice system / good fit, Farm Boy Diesel also has very affordable systems. I like my Aluminized MBRP and would purchase it again. Very good fit, no problems what so ever, it also has a 1 piece tail pipe over the axle, which I prefer. Some folks like the two piece tail pipe because it is more forgiving as far as fitment.
Whatever system you purchase, I would recommend band clamps vs u-bolt crimp type clamps. The band clamps are more expensive, but you can take them apart very easily, like you want to do with your cat-delete pipe.