Marcum all the way, a couple quick reasons, adjustable zoom on the lx3 is way, way better than only the bottom 6 feet, seperation on the Marcum is much better, the vex almost looks blurry next the the marcum. I had one of each, and I just like everything better about the Marcum, better case, better charging system, better seperation on the graph, and I could see fish tight to the bottom better than the vex could. Like I said I had them both and compared them side by side, and sold my vex, never to look back, not that I was unhappy at all with the vex, the marcum just offered better and more bang for the buck. Durability wise, I probably have more hours on my marcum then 95% of the ones sold, I use mine year round, and have not had a problem, though I haven’t experinced it personally, I’ve also heard marcum has good customer service too, and are located up in brainerd if you didn’t know that.
I’ll be picking up my second marcum this winter, so I can have one for wife and me.