If the native pixel size of the panel is 1080 on the vertical, then because 720 is ⅔ of 1080, 720 would not scale evenly and look crap. Therefore 1080.
If I instead had to choose between two netbooks, then 1) whichever has PPI in the sweet-spot of 100-120 (or >300), 2) IPS or VA over TN.