The only best site and town ship in north is swiss town/hollywood town. But its for ultra rich people and the site prices are really high.

Hope it helps

I strongly believe 4th,5th and 6th and 7th blocks are good to invest. I am a big fan of 5th block as some of the sites are in elevated area
and have beautiful view of the entire layout. (If you have a balcony in the future, you won't regret)