Is this a good rate for refinancing

Here is the rate I got this morning for refinancing:

5 year ARM: 2.75%
7 year ARM: 3%
15 year fixed: 2.875%
30 year fixed: 3.5%
Closing cost: none

I plan to sell the house in 5 years so I'm leaning toward 5-year ARM or 7-
year ARM. Are these quoted rates competitive? I checked Zillow mortgage
market place -- some of the rates look low, but they seems to be unrealistic
. Anyone?