A lot of that depends on what kind of disc-printing equipment you have, if any. Us Europeans have a nice range of Canon Pixma printers with disc-printing trays, so for example, for me, Inkjet Printable, or Hub Printable is the way to go. Others will have some class of thermal printer, and so will tend towards thermal printable discs.
White vs. Silver (either Inkjet or Thermal) simply means what colour of background you want on the printing surface: white is better if you want to print picture-based material to the disc, silver if primarily text, or if for any reason printing to a silver background is preferable.
You can use inkjet printable discs with a regular disc marker or Sharpie, it works very well, and I did this before I got my Pixma.
Watershield is a new inkjet printable technology: I actually just got some Watershield printable TYs and the surface is far superior to normal printables, it's glossy and smooth and the ink, from either a printer or a marker, seems to settle just below the gloss and it looks really good and professional, that and the watershield surface is supposed to protect the printed label from wet etc. which I can believe it would!
With the Watershield discs on Rima you also have the option of buying a 50 pack, although it is slightly more expensive.
From your post though I imagine you do not have any disc printing equipment in which case your question may well be academic, so the only thing I can really add to advise you is this: Since CDs work by placing the data layer on top of a single polycarbone (rather than DVDs which sandwich the data layer between two layers of polycarbonate) and I have lost two CD-Rs due to topside data layer damage (neither were Taiyo Yudens, and this was a long time ago), these days I prefer to buy CDs that have the tops well covered - which is the other reason I only buy inkjet printables these days.
If you're not on a tight budget, I'd recommend the 50 pack of TY watershields: http://www.rima.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=R&Product_Code=1163&Category_Code=CM
If you want to get the best value for money, any of the inkjet printable 100 packs will do you well for a few dollars more than the 50 packs.