3.0 ohm will allow you a wider range of voltages to use on a Provari. It's a misunderstanding that high resistance draws more power from a battery; in fact it has less amperage draw from the battery, which is the real battery drainer. Having said that, I suggest trying both 2.0 ohm and 3.0 ohm to see which you may prefer. (see below chart) You should find that a lower resistance will provide a warmer vape, a higher resistance to provide a cooler vape.
I use Ikenvape standard resistance cartos (Platinum 2.5 ohm/ 510 Fusion 3.0 ohm) because I prefer a cooler vape. I no longer need my vape to be as hot as an analog was to enjoy it. My backup carto is the Smoktech 3.0 ohm single coils.
I have both the Siam Mods and Slap Yo Moma tank tools. The SYM is a far better designed tool in my opinion.
I've written a cartotank setup guide which has become popular here on ECF -
http://www.e-cigarette-forum.com/forum/blogs/baditude/3710-5-cartomizer-tank-setup.html
The safe vaping power chart is a useful guideline for vapors new to variable voltage/wattage. Find the ohms on the left and the range of voltages you will use at the top, meet them at the middle of the chart to find wattage used.