In my opinion, in games I've messed with that are close to ROR, nothing comes close.
BeamNG seems to be getting more and more advanced with each update. It's also running worse on my mid-end PC. It seems many of its creators originated here (and I've been playing ROR since 2009). I did buy a new Acer gaming PC (i7+, 8GB RAM, Nvidia graphics) on sale, but the RAM was bad out of the box--and I was going to upgrade it anyway, so guess I need to get at it. ROR is completely free--I think BeamNG was something like $25. BeamNG--lags and crashing regularly. It seems I've had more bugs due to BASE GAME (not mod) vehicles becoming broken due to updates. Virtually none with ROR. Even with some high detail vehicles, and the latest ROR version, I get 50-60 FPS with ROR on my six-year-old i5/integrated graphics/8GB RAM Asus. And, certain vehicles, I've noticed originated here as well--such as the Gavril nameplate, and I feel the Civetta Bolide looks awfully familiar. Trucks and heavy equipment with complex, realistic functions are nonexistent. ROR has focused on those since the start. As I matured (from a 13-year old teenager to a 23-year-old young adult now), I've found the "crashing" gameplay more and more less satisfying, as opposed to just driving. And don't even get me started on the attitudes and behavior of the BeamNG community compared to here...
Farming Simulator. I do enjoy this game as much as RigsOfRods, even though I do run equipment on an actual farm (garden tractor, Kubota RTV, Deere 3038E, while I can drive a Deere 5400, I don't like dealing with the clutch). My favorite part is that the mouse works the loader/hydraulic controls, just like the joystick on actual tractors. ROR has forestry and tillage/agricultural equipment, but most of it doesn't work. In Farming Simulator, it does. And, there's a challenge to it. Like actual farming, there's little money to be made, and equipment is expensive as heck to purchase and maintain. I mostly use modded tractors, representing the '70s and '80s.
BrickRigs is a silly game for kids in my mind. Yes, the LEGO-type assembly method is something I'm reasonably familiar with (with me still being a LEGO enthusiast to this date). Yet, the way the game is set up, and specific game modes make it much less of a simulator. Thus, I've practically written it off.
SimplePlanes, as an engineering enthusiast, I quite enjoy. It is even used in schools. While I have built and modified a few ground vehicles, the game is focused on aircraft and the maps are designed mostly with aircraft in mind. Crash and burn are basically what ends up happening. I need a joystick...