If you want to trade an equity that reflects changes in VIX, what is a good proxy for it?
There is no good proxy for VIX, because it is a completely made-up value.
Most listed options trade on an underlying security. I can therefore choose to buy either the stock, or a future or option on that stock. In this way, the future and option are derivatives in that they derive their value (in part) based on something else, in this case the stock price as of now.
VIX is a different entity altogether. It is based on the volatility of the market, using "market expectation of near term volatility conveyed by stock index option prices". But the FAQ goes on to state that they are adding factors into the formula.
So right away there is no one equity/stock that you can hold that will necessarily match the VIX in any significant way, because it is not directly based on stocks, but indirectly through other options and computations.
In effect, therefore, the VIX in indeed only available through its options, and is not observable (tradable) in and of itself.
I'd look at VXX, I believe it closely tracks what you are looking to do.
However, as already noted in other responses, this isn't trading VIX itself (in fact it is impossible to do so). Instead, this ETF gives exposure to short-term SP500 futures contracts, which in theory should be very correlated to market volatility.
If you want to trade to gain from short-term volatility, you can use Derivative-based ETFs that try to track the inverse of a broad index like the S&P 500. Note that these ETFs only track the index over a 1 day period, so you shouldn't hold these.
If you're looking for a longer-term investment strategy, look at low-beta stocks, which often do well or produce dividend income during volatile times. Examples include McDonald's Corp and utilities like Consolidated Edison.