The main issue seems to be that the chipset fan is extremely loud and high-pitched (it's 30mm and spins at 8500rpm) and breaks down quickly. I've seen tons of complaints about dead fans on this and the other two original A8N boards. Also, a lot of memory won't run at all at a 1T command rate and the HT speed doesn't go much higher than 250, if you are looking to overclock.
There isn't any one best choice for A64 motherboards. They mainly differ in their overclocking options/capabilities and integrated peripherals like Firewire, onboard audio and so on. They all have a few quirks, so it's a good idea to do some research on any board before buying it. I think the best options are the Asrock 939Dual-SATA2 if you don't want to overclock (although it works well for mild/moderate overclocking), as it's very cheap and slightly outperforms most of the nforce4 boards at stock settings. The DFI Ultra-D is a better option for heavier overclocks and is probably the best overall nforce4 board despite being somewhat expensive.
There are other good choices too, depending on your price range and what exactly you're looking for in a motherboard.
