This question is a little simplistic. On the one hand, one can never have too much "power", even in a street car, since "power" can get you out of bad situations quickly. There are many situations when accelerating out of danger is more effective than braking and praying.
On the other, of course, less than 30% of the power output of a higher HP car is actually going to be used 95% of the time on Sg roads. From that perspective, it's a "waste" unless the car is driven illegally (which everyone frowns on) or tracked (which only the next prospective owner might frown on, if he found out).
Notice that I put "power" in quotes in the first para. This is because I actually intended that to signify what the common driver thinks of as power, but is in fact a combo of different things, chief among which is low end torque. Low-mid range torque is actually far more important than just a horsepower figure. The latter just gives you bragging rights, but the former actually helps you accelerate out of harm's way, especially at legal speeds.
I've known plenty of highly modified cars with aftermarket big turbos putting out very high whp dyno figures that are a total drag to drive on the streets, simply because the car moves at a funereal pace all the way up to around 5000 revs. A car like this is definitely not useful on the street - it simply won't get you out of a pinch at street speeds. So it's really low-mid range torque that matters more.
And other factors matter too. Weight is just as important as torque (and power) - in fact, one should always be talking about power/weight and torque/weight ratios. In fact, given equal power (or torque)/weight ratios, I'd rather take the lighter car (even if it has lower power/torque figures) because it's going to be just as quick in a straight *and* handle much better. Light, nimble cars are the way to go.
And of course, braking is important too, for obvious reasons. And the quickness of the steering.
Short answer: I don't think this poll is asking the right question. But if I had to answer, I'd say the more power the better, as long as it's coupled with added torque in the usable rev range. That's a rare thing, actually.
Edited by Turboflat4, 09 June 2013 - 01:10 PM.