Aren't collars equivalent to bull call spreads? I can't think of a reason to trade the collar unless you are working in a retirement account that won't let you trade spreads.
I would only trade a collar if the skew, borrow, or expected distribution provided value to just owning equity.
If you already own a stock, especially highly appreciated stock, collars are a good way to protect your gains. You can create collars on individual stocks in your portfolio, or you can create a collar on a broad-based index (i.e. S&P 500) that is highly correlated with your stock portfolio. The latter will save you transaction costs / commissions. Depending on your strike selection, you may be able to put on a zero-cost collar, where the cost of the put is offset by the premium received from the short call. But you will have to give up gains on the upside (due to the short call), and may lose some money on the downside depending on how far the put is OTM. <a href="http://www.optionstack.com"> Options analyzer software </a>