I have low-end Shimano (Altus) on my commutermobile and mid-price Campagnolo (Athena) on my road bike. The difference in smooth/quick/accurate shifting is amazing!

That being said, I don't have issues with the cheaper components. They are just slower to shift and sometimes need a little babying. And the price was right.

If you can, ride similar bikes with different levels of components until you find the level that feels good and is within your budget.

I second the pedals: if you are used to them put them right on your new bike! Also if you have a saddle you love, put that right on the new bike, too.

Have fun!