You should look closely at the LHT. Only reason to look at Troll is if you intend to run an internal gear hub or SS, and/or if you intend to ride primarily off-road. Those big tires are nice on rocky terrain but a major energy suck on the pavement.

If you are always going to run derailer(s) then LHT is a better touring bike. LHT has a shorter reach than Troll, as it is intended primarily for drop bar use, whereas Troll is more of a MTB intended for flat bar. LHT has 46cm chainstays, Troll has 42cm CSs, thus more likely to have issues with heel strike depending on rack, bags, and bag placement. Wheel removal/flat repairs with fenders and vertical dropouts on the LHT are easier too. LHT 26" is perfectly capable of handling most any navigable trail, dirt or fire road.

Surly is owned by QBP, worlds largest bike parts distributor, and they probably sell >10X as many framesets and bikes as VO. Surly frames are built by Maxway, the leading bike frame builder in Taiwan. It is hard to imagine an advantage going with VO, unless you just really love a specific feature or the finish color. Like the Troll, I notice the Piolet has 42cm chainstays (too short for most panniers). Troll and Piolet come in 5 sizes, while LHT comes in 9 sizes and is more likely to fit well. If you expect to ACTUALLY RIDE this bike for 5-7 hours a day, day after day on a long tour you will definitely want the best fit possible.