Which financial metrics to use when deciding to keep or sell a rental

[John Lubin]

When evaluating each of the rentals in your portfolio (presumably on a yearly basis?), which financial metrics do you use to decide if you should keep or sell a specific property?

For example, do you look at Return on Equity, Return on Invested Capital, etc?  If I look at ROE, I might realize the house has appreciated and I can take that equity to get a better return by selling the house and investing in another property elsewhere.  (Of course there are sales costs, tax implications, etc).

Thanks!