I have never been on a rough Intamin, but I have been on some rough B&Ms. However, the smooth B&Ms I have been on left me with the feeling of "Wow, that was extremely smooth!". But I have never had that thought on an Intamin. While smooth, Intamins are just not *as smooth* as the smooth B&Ms. On the other hand, I find B&Ms to get rough in older age. I think Iron Wolf and BTR at SFGAm are both fairly rough after the 10+ years they have been around. But the newer B&Ms are very smooth. But Intamin also has some examples of rough rides (I have never heard a good comment about SFMM Flashback). But, in recent years, the new Intamins that have been created are much more smooth than the coasters that they used to construct and I don't have any example of one of the recent Intamin coasters to be in *old age*. Now that I have gone on long enough, in the end, winning just slightly, I would say B&M.