If you have a Dymo LabelWriter printer, you're going to need labels for it or it will just sit on your desk gathering dust. I don't know if there are alternative brands out there, but I always buy Dymo labels.
I always choose the Large Address Labels, which are 89mm by 36mm. This is a fairly typical size for an address label, and is therefore the right size for most addresses.
For the last six months or so I've been using the clear labels, for a particular reason. I organise several large internal conferences a year, and someone suggested using a label printer to create onsite name badges - print the label then stick it onto a blank badge. The white labels looked a bit too obvious for this, so I started using clear labels instead, and I've continued using them for normal use as well, as it's not easy to change the roll in the printer.
The white labels are very slightly glossy. The address prints onto them very clearly, as you'd expect given that they are by the same manufacturer. There is never any wet ink as the label printer uses thermal print, not ink, so you can use them as soon as they finish printing without worrying about smudging them.
The clear labels are matte in finish, and appear to be more opaque than clear, as they look a little like frosted glass. However if you stick them over other text or printing, it shows through very clearly. The matte finish works particularly well for the name badges I mentioned previously, and it blends in well with the white matte card that forms the badge itself.
The large address labels come in a roll of 260. They're a bit of a pain to get into the label printer, something which I mentioned in my review of the printer itself. Once I do eventually get it going though (and I attribute the issues with that to the printer, not the labels), the labels feed into the printer fine, and come out the other side no problem. The only issue I have in this respect is that once printed, the labels are still very curly from being on a roll. This isn't a problem for a few, but there have been occasions when I've been printing 50 or 100 in one go, and I end up with a big curly mess of labels on my desk, which can get quite tangled.
These are good quality labels, and are not easily torn. I just tried it - I thought I'd better test it for this review, and I couldn't tear a label.
There may be alternatives available to use with the Dymo LabelWriter range, but these Dymo labels are good quality and you know for sure that they are compatible with the printers. I will continue buying them, as they ensure that my address labels and name badges are all printed clearly and legibly.