Welcome! The actual juice you choose to vape is certainly at your taste's discretion. There are MANY different types of juice. However, with your blu ecig, you might consider finding empty cartridges that you can fill on your own.
You can get into the e-liquid section and see all the different vendors and flavors of juices that could be out there. I personally was a menthol smoker, but I really don't bother with any kind of tobacco-flavored juices (I do have a couple, but they're on the very bottom of my preference list). I enjoy desserts, coffees, and fruits as my different choices.
Someone wiser than I can confirm the threading on the blus, but I was thinking they're 510 threaded. You should be able to locate refillable cartomizers (which can bring down the overall cost of vaping.) I've seen a few threads that there might be some local vape shops in your area. If you can walk into an actual B&M (Brick & Mortar storefront), they might have a "tasting" bar where you can try all different kinds of things to see if there's something else you might enjoy along with the menthol flavor.
I could ramble on about upgraded hardware, but it might suit you to find flavor(s) that you like and refillable cartridges. If you think you've outgrown the usefulness of the blus, you can certainly come back here and see all the different kinds of "toys" that folks have. (I started with something similar to a blu, and have since upgraded all kinds of things - I completely quit smoking real cigarettes 7 weeks ago, and I enjoy all the different nuances of different flavors and such. My current mods (batteries) have longer lives - don't need recharged as often, and the tanks (things I fill with juice) don't have to be refilled quite as often as my older cartridges did. So for me, this is less of a hassle to continue doing.)
Good luck, and happy vaping
