Depends on your price range really. Nicholls is a really good suburb all round so you cant go wrong really. Its pricey -though! quite a few $1 million+ properties in Nicholls! Coming down from that in the $850 to $750k - Anne Clark Avenue - Lexcen Avenue - Freda Bennett Circuit - all really nice streets. The great thing about Nicholls is that its an older suburb in Gungahlin - alit of the properties have more land space - which essentially means you get a backyard! And if you want - a pool!
Cant go wrong with Nicholls. We have lived here for 8 years. Lovely area.