I absolutely love nickel Lo Riders. They're my favorite string based on their relatively warm and round sound (the stainless steel Lo Riders are REALLY lively sounding, great when you want that kind of sound but I don't right now), their pretty stiff feel, and the remarkably long life I get from them. I've had them on most basses I've owned and have always gotten great sound from them.
I haven't used the Rotosounds before, but I've had the impression that they don't last as long so I haven't given them a shot yet. Maybe I should because I do love the sound of a well broken in roundwound string once the new string zing is gone - most of the time. I've tried both EB Slinkys and Cobalts but, to me, they went dead way too fast and not in a good way. I also remember them feeling pretty flexible, so I have multiple reasons for never going back to them.
I know I've seen some people post about the relatively stiff feel of GHS Pressurewounds, but I notice a difference in feel from the Lo Riders. I've only tried them on my Stingray and even tried them a second time recently but, to me, they feel noticeably more flexible than Lo Riders. They're not so flexible that I'd rule them out (I bought three basses that had TI Jazz Flats on them at the time and I will never buy the TIs - WAY too floppy for me!), but I prefer strings that are even stiffer than the PWs. I'd say they're about as flexible a string as I'd want to use, but I prefer even stiffer feeling strings.