Heavenly has the best views in my opinion, but I'd rather ski a better mountain with slightly worse views.
The view of the lake as you ascend the Gunbarrel chair is unmatched. The view of the entire Tahoe region from the peak as you traverse from CA to NV is breathtaking. The mountain, however, has...issues. I despise Heavenly's layout. It's extremely compartmentalized which makes top-to-bottom runs nearly impossible and creates massive bottlenecks of skiers in certain areas.
The views from the north shore, at Squaw and Alpine, aren't quite as impressive, given the 5 or so miles from their bases to the lake, but they are still breathtaking and the mountains are far superior.
Surprisingly, though, the Tahoe view that sticks the most in my memory was a warm April day near Incline Village. Heavenly was clearly visible some 20 miles across the lake but that's not necessarily impressive. What sticks in my mind was the fact that the bumps on Gunbarrel were visible from that far away.