You'll get many replies and recommendations to this question. This brand, that brand, you get the idea. Some folks love to get into the "finer-points" of a 35db fan vs. a 36db fan...like anyone can really tell the difference!
As a general rule, Ball Bearing fans are better than Sleeve Bearing fans. Less drag, smoother operating, more RPM and longer service life. Generally, BB fans are about $2 more apiece and worth every penny.
I'm on my third Antec case (well, two for me, one for the GF) and have used nothing but Antec fans and have had no probs w/them.
The Panaflo fans are supposed to be very quiet, but if you've got more than two fans running...you're gonna hear the air "whooshing" no matter which brand fans you use.
I have the Antec SX1040 case and am using four Antec Ball Bearing fans. Good to go. Yes, I can hear the "whooshing", but I also have a FOP32 which makes a little noise on it's own.
Buy ball bearing fans from a reputable, well-know company, period. Antec's work great for me. IMO, don't waste your money on the super-duper-high-output-magneto-drive-abso-silent fans.