Camera without the Z axis....
Hold alt + drag from left to right ANYWERE in the viewport and affect ONLY the y rotation of the camera's orbit.
Dragging from top to bottom ANYWHERE should rotate in the x axis.
A.K.A. Camera controls that resemble: SUBSTANCE DESIGNER!, Mudbox, Maya, 3DSMax, Unity, like 90% of other 3D programs, etc.,
I've never wanted to adjust z axis casually, it is immensely frustrating now that I can't avoid it... Just an option to make your app less painful.