the vape goes to 100W, so would 2500/3000mAh be okay?
Unfortunately, the '100 watts' refers to the capability of the mod's circuit board and fails to account for the fact that there is no 18650 that can safely provide 100 watts. The highest you should get with a single 18650 is 90 watts, but if you choose those batteries you won't get much battery life. If you limit yourself to 75, 60 or even 45 watts, your options start to improve.
At 75 watts, you're looking at around 2,500 mAh, but that doesn't mean that any battery with 2,500 mAh will do. Some models will simply fail to fire your mod, some will work well, some will work poorly and some will come with the risk of blowing themselves (and your face) to bits at 75 watts. That's why we're asking what wattage you want - so we can recommend a specific battery make and model that should work well for you.
It's also really important to buy your batteries from a reliable vendor. Counterfeits abound, and you want to reduce your risk of ending up with one. Some of the better vendors are listed in the blue row on the chart
@UncleJunkle posted above.
So, pick your top wattage and we'll be happy to tell you what you need to look for. Good luck!