I take it you are using pedals also. The TH warthog does not come with Z axis (rotation for Yaw control). The VKB gladiator does if you buy the " GNX SCG ‘Kosmosima’ Premium Grip:" version.
I have used the TH warthog. The build quality was very good. The calibration seemed ok for the brief spell I tried it. I sold it on though due to the Z axis not being available. Other than that I had no real complaints. Buttons are a bit stiff to start, but I would expect them to loosen fairly quickly with use. The TH warthog is still fairly well sought after.
I have never used a VKB gladiator NXT.
My current joystick is the a Virpil constellation alpha with a VPC WarBRD base. This is a healthy step up from the TH warthog I had use of.