I've been using Boge LR cartos for a little while now, and while they work great out of the box (usually) they just don't last long before the flavor starts to become overly burnt/spicy tasting with a harsh TH (I can usually get a day, maybe two before they start to suck). Cartos can last a little while longer on thin clear juice, but going past that they suffer big time and don't last long before the flavor of your juice is ruined due to all the junk being built up on the inside that cannot be cleaned out.
And tanks? Nope! I thought a carto-tank was the right thing for me, but you will end up hating whatever juice you use in a tank cause for whatever reason it funks up the cartos big time as the spicy/burnt taste and harsh TH is amplified by 10 fold after tanking for a day or two. You will get more life out of them by filling normally than by using a tank.
The next step for a Boge carto user is a
clearomizer/fluxomizer (Gotvapes has a great selection and has the most up-to-date clearomizers available
GotVapes™ Cartomizers : GotVapes.com, E-cigarette Supplies - Atomizers Cartomizers Mods Juice and more).
You can see your juice level so no more guessing when you need to refill or worrying about burning the filler (the wicks in clearomizers don't burn), clearomizers can hold a great deal more liquid than cartos, anywhere between 1ml to 5ml (or more if you do your own tank clearomizer), you can use every last drop of juice in a clearomizer (since there is no filler to burn if it gets too dry), and you can thoroughly clean them out and re-use them for a long time with relative ease (unlike cartos, which are pretty much one-time/one-liquid use deals and even with strenuous cleaning attempts, still never taste right).
Sure a clearomizer might require more fiddling than a carto, but in the end not having to worry about your juice taste being biased to the filler, potential burning of the filler, or burnt gunk build up after a day or two of use, is a much better solution. Using more than one flavor in a carto is generally a BAD idea, even if the flavors are similar. Clearomizers can be completely cleaned (syringe plunge + dry burning) and don't require fillers that can potentially hold old liquid and ruin the flavor of a second liquid choice. You can actually dry burn a liquid out of existence with a clearo.
Clearomizers basically take the best parts of dripping on attys + cartomizers, and combines it into one device that surpasses both those options.
Attys+carts -> eGo tanks -> Cartomizers -> Clearomizers.