Personally, I love my SD2IEC device by Jim Brain (uIEC)... super easy to transfer standard disks (or individual files) between my PC and my Commie. However, it gets technical with heavily-copy-protected disks (those that need GCR instead of D64/D71)... lame copy protection works fine with D64/D71.
My 2GB SD card holds all classic 64/128 software, plus all my *bloated* C128 Videos... if you have 4GB or 8GB SD-Card, then I think it would hold *everything* your Commodore might ever need!
I've read about 64HDD, and it seems like a nice product... but it seems (in my imagination) very difficult to transfer files from a PC to a CBM... well if you have CMD-HD with an attached SCSI drive to swap with your PC it might be the same... but few Commodore owners (AFAIK) own a CMD-HD, and similar few PC owners have a SCSI hard drive (typical EIDE/ATAPI); thus few *times* few = rare!!