In general? Older vs. older? New vs. new? Speaking year of production wise. I have to ask that because I have not personally owned a Radice made after the early 90s (owned several of those), and I own one newer Castello now, which is a fantastic smoker. All the others were older Castellos. I've never owned a poor smoking Radice. They were all at the top of my collection. I've also never owned a poor smoking Castello, but I have owned several that were consistently ho-hum smokers. My Radices were unusually lightweight wood, while I seemed to run into slightly heavier Castellos. Not all of them, obviously, but it was something I noticed as they came my way in trading etc. I've always thought that had something to do with how they were curing the blocks. None of this is helpful if you're looking to buy a brand new pipe. Sorry about that. I wouldn't hesitate to buy either brand. Radices are probably one of the brands of today that are on the better value scale (overall speaking), especially because I feel some of the pricing for Castellos is outrageous. On the other hand, I have a difficult time finding new Radices that are as appetizing as new Castellos. I see lots of new Castellos, of many variations, that I think are very sharp pipes. Not so much for Radice. I don't see either as better than the other, but they certainly hit different price points.
I should also add that I've owned a few older Il Ceppos. Beautiful pipes, but like my experience with Mastro de Pajas, I never owned one that was an impressive smoker. I personally consider both Radice and Castello to be a few cuts above both of those brands.