Better is subjective to use and intent.
The 13" base model is only 100$ more than the 11", and also has the 12hr. batt life in I5 configuration, that being said with larger screen and much longer battery life, you might consider the 13"
Having both the macbook Pro and Macbook Air, I use the Air almost exclusively. the Air has a SSD with extremely fast boot time, and is a powerful platform nearly the same as a base model macbook Pro but weighs a great deal less.
The new AIr is the only Mac that has Haswell processor, extremely long batt. life and 802ac next gen. wifi.
As to the 11" vs. 13", that is subjective, ....Ive owned both 11" and 13" Air, .... certainly prefer the 13", however you may differ on this.
However as stated above the 13" is very little more in cost, but has a LOT longer battery life than the 11" Air.
Remember the RAM is not upgradable, for a minor price increase, consider getting the 8gig of Ram vs. the 4gig base model. That being said however the 4gig of Ram is plenty enough for most everything in general use.