A real step up from LT, but significantly lower cost than a fully kitted provari, would be the notcigs Infinity Pro. $120 delivered, with two sets of batteries and charger (coupon code "ECF Buzzkill", 2 words). If your LT charger is a 2-bay unit, you could likely reuse it, skip the charger, but like most things a backup is good to have.
3.3 - 5.5V, 15W maximum power, no voltage sag as the batteries are used, simple wheel interface to change voltage, rugged, good safety features. I get about 6.5ml of eliquid through on one set of batteries, at 4.5V with a 2.5 ohm carto (just over 8 W).
Notcigs came out with the original production VV, the Buzz. They've kept their focus on high performance, rugged, products at good prices.
I'd study up on the Kick. While I don't change power/voltage from vape to vape, I do find I'll nudge it up and down multiple times throughout the day, just depending on how much warmth/vapor I want at any time. With the notcigs products, or the Provari or Darwin, adjustments are easy, but from a review by Cyberwolf, "...Minimizing the necessity of changing the voltage is a good thing in this case. Due to the nature of the Kick being an internal modification to an electronic cigarette, the device must be taken apart to access it. Once the Kick is exposed, a small screwdriver is needed to change the power setting via the dial on the potentiometer." The review was overall positive, but having to take things apart to change voltage and go to a smaller battery to get the Kick to fit inside a PV are things I wouldn't want.