Output the largest number with the fewest digits
Pyth, 7 3 6 bytes

eS.ml`


Test Suite

Explanation:

e      Still grab the last element
 S      Still sort
  .ml`   But prefilter the list for those with the (m)inimum length.




7 byte solution:

eSh.gl`


Test Suite

Explanation:

   .g   Group items in (implicit) input by:
     l  The length of
      ` their representation
  h     Get those with the shortest length
 S      Sort the resulting list
e       and grab the last (i.e. largest) element