Brand names are less important than the source. Having said that, I have always had good success with Sony and Imation (3M) and TDK brand ones.
What I find more important is where you buy your CDs. I stopped buying them at my local Target store. Too many duds. Frankly, I don't think their warehouse is climate controlled or something. I've bought the same exact brands from Wal-Mart and Office Depot, and had no problems.
It could be that your cd burner is slightly out of alignment? Some CD drives are more forgiving than others.
Frankly, I've been experiementing with LightScribe (http://www.lightscribe.com/) and I think you can do some really cool stuff with burning images on the top of the CD. HP and TDK and Verbatium all make LightScribe media. If you buy a second drive (say an external USB model - that should be easy to add on), you might look into one that can do LightScribe.
PS: If you get into DVDs, I would stick with DVD-R. Many devices today can use DVD+R, but those that can do DVD+R can typically do DVD-R too, but if your device only does DVD-R, then a DVD+R isn't going to work.
PS: USB Flash drives are cheap enough these days, particularly if you buy in quanity. Perhaps the easiest thing to do would be to switch to Flash drives. You can even buy them with your logo printed on them, etc. The down side of these is that they can be erased, but you could encourage the client to burn them to a CD themselves. Just a thought.
PPS: I use mkisofs (a command ported to Windows from Unix) to make the ISO image. This allows me to put both Joliet (used by Windows) and RockRidge (used by Unix and Macs) extensions on, and make it ISO9660 compliant. Some Windows based CD burning programs just ignore whatever parts of ISO9660 they don't like, which makes a CD that claims to be ISO9660 compliant, but isn't. Some CD reading software is okay with this, some barfs on it.
mkisofs -iso-level 1 -J -R -p "your name" -P "your name" -V "volname" -o file.iso ./directory
"volname" is the volume name - do yourself a favor and stick to 8 characters, lower case. The -J says to add Joliet extensions, the -R says to add Rock Ridge.
Then you can use any software you want to burn the ISO image to the CD.
mkisofs is part of cdrtools, formerly known as cdrecord:
http://cdrecord.berlios.de/old/private/cdrecord.html
http://en.wikipedia.org/wiki/Cdrtools
You can find various graphical "front end" programs for cdrtools on SourceForge http://sourceforge.net/ - it is not for everyone - it is a command-line type program, but it works well for me.