If you like your smok X8, then I tend to view you as a sub0hmer, really, although it does seem you are also asking for more flavor.
Honestly, I would look into buying a reliable two battery (external) mod, and I might suggest the Original Uwell crown if you can find it, as it has a wide variety of coils, up to 1.2 (I think, I don't own this tank) and try the coils to figure out which resistance suits you best. It's generally reported to be a flavor tank and the coils get good reviews on longevity. Plenty of affordable 2 battery mods out there, although yes, you will have the added expense of buying batteries and a dedicated charger, but it's important to use a reputable battery vendor, etc. This blog is very informative re: batteries and you will find a chart listing testing of all the major batteries and in the last cell, reputable, authentic suppliers are listed.
Mooch's blog | E-Cigarette Forum
If you really want to try more restricted vaping, you could try a Nautilus 2, it really is a dedicated MTL tank as far as setup, but it does also come with a 0.7 coil. That topper is pretty inexpensive if you want to move toward MTL vaping, but do not make a mistake-- you will be inhaling much less vapor than in your current setup, the draw will be different, and to compensate for less vapor, most vapers using this type of setup find that they need a higher nicotine level.
Sorry to not have more suggestions, it's a little hard to know which direction you want to go in. I do think this type of setup offers you the most options, it's variable wattage and a two battery mod will give you enough power to vape through the day, probably, and most definitely if using a more MTL tank and coils. I'm just not entirely clear which direction to go in, and how far. I'd say the Crown tank may be your best bet, if you are enjoying your current vape.. If you want to get more restricted even further, well, there are tanks for that, and the N2 is as good a place as any to start.
Best of luck,
Anna