I use blue, would like to use def at the pump since its cheaper but its at a truck stop 30 mins away and its always super busy. you can normally get it on sale at auto part stores.
Cheapest DEF I've seen in the SW has been 2.79/gal (equiv of 6.98 for 2 1/2 gal jug). Indeed at the pump is the best price I've seen and is probably the freshest. Haven't ventured to the pump yet as only the truck stops in the truck lanes are carrying there from what I've seen. None in In the RV/auto lanes yet. T/S fuel has been 12-15% higher than other quality stations, so don't stop at them much anymore.
2016 XD 5.0 Cummins Pro4x Pearl White, Build date 4/2016, Conven & Util + Audio, Bumper Step Assist, Dark Chrome Step Rails (needed someplace to clean my boots before entering!), Front & Rear Splash Guards. 2004 Subaru Forester, 99.5 Powerstroke with mods, previously a 2011 Xterra Pro-4X - (a fine vehicle but was upsized by the XD)