Well carbonation tabs are convenient forsome people but basicly they are no more than sugar just in a different presentation. If you keg they can be a good option if you have beer left after filling a cornie. I prefer dilute a priming solution in the finish beer and bottle.
Carbonation tabs (like coopers) can take a little longer to carb a beer too. And corn sugar or simple table sugar are way cheaper.
Make sure to use a calculator por for your priming sugar and account for your fermentation temperature.