I have used Tech 8's, Oxtar TCX Pros and Sidi Crossfires w/regular soles.
I weigh 270 lb geared up ready to ride and my boots typically last about a year and half before they are either in need of major repair or are unrepairable. I have found repair to be short lived in most cases.
The Crossfire durability is better than Oxtar and far better than the Tech 8's.
The Sidi Crossfires are exceptional. They are comfortable and offer a good range of motion. They protect my feet and ankles from encouters with rocks, stumps, etc far better than the Tech 8's or Oxtars. I have taken a number of hits with the Crossfires where I was expecting notable pain/ injury, and my foot came away unhurt. The buckles are excellent.
The Crossfires are the only MC boots I have ever worn that are truly waterproof. I can wade around in water for an extended time and my feet stay dry. The waterproofing only goes to to the top of the gaiter, but it really works.
I tried on a pair of Tech 10's. The ankle support was very uncomfortable.