It depends on whose perspective the question is coming from. In the current market, a tenant, if they like the terms, should try and sign a lease for as long as the landlord will give them. Rates are at all time lows and locking in a great rate can save you plenty of money. When the market recovers you can expect rates to move up considerably. If you are a landlord, shorter term leases 1-2 years make more sense. As rents recover you are not locked in to lower rates.