What are your plans in Bali?
If you are there for party only, then either Kuta or Seminyak will be good.
The main party area is Kuta, which includes dodgy bars as well. Seminyak is a nice area to stay, its near Kuta, but have nice restaurants and bars.
You can rent a motorbike cheaply in Bali, so you can travel between Seminyak to Kuta within 5 mins.
For accomodation, I personally think Seminyak is a nice area to stay because its accessible to good quality food. I stayed in Uma Sapna in Seminyak, and highly recommend it.
If you plan to dive, then you might want to look at hotels around Sanur. Accommodations are really cheap in Bali, because there are ample. If you spend a little time, I am sure you can get really fancy accommodations without burning your pocket.