CHART: The Monthly Mortgage Payment Vs The Monthly Rental Payment Since 1981

One of the more straightforward considerations is whether they can make their monthly payments.

As the U.S. housing bubble ballooned, surging home prices caused the median monthly mortgage payment to diverge substantially from the median monthly rental payment.

And when home prices crashed as the bubble burst, mortgage payments actually fell below rent payments. Scarred by the housing bubble, it was clear that sentiment played a big roll in Americans' decisions to opt for an increasingly expensive rental than commit to a home that could quickly pull them underwater.

Now mortgage payments are back above rental payments, adding to perceptions that affordability is deteriorating.

The difference, however, is pretty much negligible.

"Admittedly, despite a slight fall in the fourth quarter, typical monthly mortgage costs are above median rental payments," noted Capital Economics' Paul Diggle. "But the $45/month gap between the two is small by historical standards, suggesting that few would-be homeowners are likely to be put off by the increase in costs relative to renting."