1031 or Sell

[Hongbing K.]

I am trying to figure out which one will be a better strategy. 

I own a condo with a mortgage of 309k. This condo was my residence for 2 years before I turned it into a rental. It has been a rental for about 6 months now before I realize (learned) that it is not anyone would consider investment worthy. I know the condo will go for about 400K. 

Now my question is should I can get the money, which I believe will not be taxed because it is under $250k/$500k. Or, I should do 1031? 

I am leaning towards 1031 because I will have to use all the money from the sale. With a 400K condo value, I can purchase probably 2 or 3 rental units.