That is a very subjective question.
If your asking for 'most desired' in terms of highest values, then your talking close into down on the west side of downtown or in Westlake (78703 / 78746 / 78731).
If your looking for an up & coming trendy area, I'd suggest 78702 (the new 78703 / 78704)
If your talking rental communities, then your talking University Area.
Otherwise, it's just a matter of your lifestyle, price range, school quality, distance to employment centers & entertainment districts, etc.
Maker Capital Group, LLC
2307 Lake Austin Blvd.
Austin, TX 78703