The 997.

Both the front and rear fenders of the 997 seem stretched a little tighter than the 987, implying that the power under those wheelwells is barely contained. Also, that flat area of sheetmetal that outlines the wheelwell is a little thinner on the 997, again implying it is stretched to it's limit to contain the wheels.

The hood on the 987 seems slightly lower than the 997, producing a deeper V and making the front fender of the Boxster more prominent. That might just be this photo though, hard to tell.

I am neutral on the lights, neither seems aggressive to me. The 911 looks classic, as it should, and the 987 looks like a modern and conservative sportscar headlight design. Both look great.