Mine is actually marketed as a hybrid, not a road bike, and in its one foray off the tarred road it did pretty well.
My absolute deal-breaker was that it had to be light enough to lift into my car. I also wanted it to look and ride like a normal bike. I had a short list of five or six, but most of them were crossed off pretty easily, one for simply being twice the price of anything else! There was a Chinese-made one (Fiido) which looked pretty good, had things like a prop stand and lights and so on. I nearly bought it as the first one I saw advertised, although it was 17.5 kg, but then it turned out they were out of stock so I looked around a bit more and that was when I saw the Ribble. I think it's less than 15 kg to be honest, the lad in the shop said 13-14 kg depending on how it's configured.
You obviously have a much wider choice than we have here, but maybe your first choice is whether you want one bike that will do everything, or whether your off-road and your on-road requirements are so different that you should be thinking about two bikes, one for each purpose. If you're really going to be mountain biking seriously you probably need a bike made for that, but if you just want to ride off-road on gravel tracks, a hybrid will do very well and double as a road bike.