My opinion also would be that a condo is less liquid than single family. They can often times present a good value, but there are many rules, additional fees and prospective buyers have to worry about capital funds and special assessments.
Raw land in my area sometimes takes 5-15 years to sell unless you are willing to sell it at a bargain price ($15000/acre).
Multi-family & commercial is somewhat slow in my area. We had alot of california investors that came in and bought alot of apartment complexes in low income areas and fixed them up and now they are trying to sell them for $20,000/unit and none wants them. The complexes have been on the market for about 3 or more years.
Single family houses in white collar areas seem to sell the fastest in my area.
Single family houses in low income areas take awhile to sell and normally sell to investors.