Sparco tape is the best shipping tape we've found to date. It's thicker than most of the popular name brand sealing tapes out there (Scotch, Duck, etc. - even many of the "heavy duty" varieties.) However, the thing that sets Sparco apart from the others is that it's very, very sticky. So, if you've used other tapes that have problems sticking or staying stuck to your packages, Sparco tape might be the solution to your problems.
If there is any disadvantage to Sparco tape- it's pretty loud to work with. If you value peace and quiet or are trying to pack up items with a baby sleeping in the other room, you may want to look at tape brands that are marketed as "quiet". We haven't tried any of those, so we're not sure if they perform adequately, or if they are as quiet as claimed.
There are cheaper packing tapes available of course, but "cheapest" isn't always the best deal. A six roll package of Sparco tape normally goes for about $12 on Amazon Prime. You can find it cheaper on other sites but typically with added shipping costs. So if you're an Amazon Prime subscriber or you can buy enough to qualify for free shipping, Amazon often is the best deal. Even at $2 a roll though, Sparco tape could be considered a bit spendy (but probably still worth it if you ship things that are at least slightly heavy or if your packages are going to be exposed to high temp/humidity environments.)
All that being said, very occasionally Sparco tape goes on sale at a deep discount and if you can pick it up then, you may have the best tape available anywhere for the price. (If you know of something that's better and cheaper, please let us know!) The lowest price we've ever seen for the six-roll Sparco tape is $6.99 and for that price it's a steal. If you see it that low, stock up because that sale doesn't happen very often.