Driveclub is the best looking next-current gen game. Easily. Anyone that says otherwise is either blind or biased. Really no other way to put it. It also features some truly incredible weather cycles that also surpasses all other games. Driveclub is as everyone knows also 30 FPS.
Forza Horizon 2 is probably next on the visuals, although truth be told the environments are not wow by any means. It is however also pseudo Open World, so that is very impressive. It is also 30 FPS.
Forza 6 is next visually. It looks pretty damn good. It is however as everyone knows 60 FPS. It is sacrificing some visual fidelity for performance, and many people consider it to be the best from a gameplay perspective because of this, but there is no doubt whatsoever it does not look as good as DC.
Finally the new Need For Speed looks like it is going to be some serious competition for DC, but the verdict is still out on that as all we have been shown are promotional videos and do not have the actual game yet to make a final decision. It is also apparently all at night, which one would have to think gives the developer a little less to worry about and lets them focus on getting the most out of the engine.