I haven't had a need to make refractory veneers since I started using e.max. If I never had to make refractory models again that would suit me just fine.
I wouldn't say they are better unless you do a thin Emax shell and layer. I'm not a fan of monolith veneers but a layered Emax is pretty close to the quality of refractory veneers. The problem with refractory veneers is that its very technique sensitive so the learning curve is longer and maybe a bit more labor intensive unless you are a pro like the guru's.
I use both. Emax is way easier, however if I work off photos and have to mask out areas of tooth I go for refractory as I'm only masking small areas and not the whole veneer surface. I can't stand the messing around with margins doing refractory, it wastes so much time and sometimes - crack!