While speakers make the most difference, you seem to have two goals. For dynamics, I'd recommend dropping that into a a GOOD sub, such as SVS or Hsu*. That sub should hold you through several upgrade cycles,
Go for that first and see how you feel. Then, we can talk about different speakers but, be aware. they can run into big $$ considering that you'll need to go for the three front speakers.
* Others may suggest other brands as well. Consider their advice.