I like to buy land then build as you only then have to pay stamp duty on the land component not on the whole land + house as you do with established properties.
Of course you do have holding costs during construction but you also get to reap the rewards of tenants loving new properties, higher depreciation, warranty periods on appliances, builder warranties and generally less maintenance as everything is new.
I'm not keen on buying land and doing nothing with it - you can't claim any negative gearing on it and I see little point to it.