Macro is a broad field and much depends on the kinds of subjects and shooting situations you're most interested in. Factors to consider are magnification, working distance, ruggedness, convenience/handling, and of course cost. Hard to beat a weather-sealed dedicated macro lens for ruggedness, convenience, and handling. That the Pentax 100WR doesn't have an aperture ring is a drawback, but a small one in my opinion, because there's not much reason to reverse a 100mm lens, while normal extension is still possible with A-type tubes. Coupled with a Raynox for extra magnification and you have a versatile macro rig.
I say this having never used the 100WR or a Raynox.
I have macro lenses ranging from 50mm to 100mm plus an assortment of tubes, bellows, reversing rings, etc. My choice of gear for a particular session depends on the factors I listed above, and I find it useful to have a range of options.