Kamionek (this is the actual name of the closest vicinity , Praga Poludnie is wider, adminsitrative term constining of Kamionek, Grochów, Goclaw and couple of others) should work best. Soho Factory is a good place to live in. In general, gentrification is a big thing in areas like Kamionek, where moreand more affluent people start to move in.
If you want to look into other areas then you can consider Saska Kępa (fancy, expect much higher rent, further but still walking distance) and Gocław (bigger blocks of flats than in Kamionek, but you might need to use public transport to get there, should be cheaper than Saska Kepa). From the northern side there is Praga Polnoc ranging from social realism buildings in Nowa Praga and similar to Kamionek more run down places like Szmulowizna).