The smell from your device depends more on the material you use and how you use it. If you do not exhale visible vapour, the LB is virtually odourless.
I'd have to agree with that opinion.
Which unit gets the most out of your bud while making it last the longest?
Depends more on the user than the vape being used. Any model with temp control via dial or display is going to be easier to use efficiently, since you can use the unit to control temp, and not just depend on your own estimate of how long to apply heat (battery connection time on the MFLB). OTOH, it's very easy to load small amounts in the LB and take small hits. With the V-Tower or Extreme (or other home unit with a large bowl), there's a tendency to load big and hit big. Loading small amounts in a full sized vape is doable, but most don't do it. It's much less satisfying that way. So with good quality models, efficiency can be more about how you use, than what you're using.
When it comes to getting you high, which unit does it best?
Again, the answer is mostly psychological. Currently I'm mostly using (at home) a PD, with a very small bowl, and an SSV, with a largeish bowl. I get higher quicker using the SSV (even using a temp setting that corresponds to the PD setting), not because it's better, but because there's more herb in the bowl and I can get bigger hits. So I'm getting more vapor in a shorter time period. I can just as high from the PD, but it takes longer since I have to reload the small bowl multiple times. What ends up happening, with the PD, is that I tend to stop my session before I get to the amount I vape more easily/quicker in the SSV. I stop because I don't feel the need to vape anymore, not because I've vaped as much as I would have/did vape in the SSV.
Vaporization is a fairly simple process, and most good models do an efficient job of it. The difference between most models (aside from temp issues) is how the vapor is delivered to the user. Small vapes with small bowls and narrow vapor paths will tend to stretch your supply, since you're getting smaller doses with each hit, and you may be quite satisfied for a while after vaping a fairly small amount. You just won't feel the need to load another bowl right away. If you're using a bigger bowl, like the V-Tower, you'll tend to load more and take bigger hits, getting higher quicker but also using more of your supply. You can also go through herb quickly with the LB, since it's easy to apply heat quickly and connect the battery long enough to get into high temp range, and you'll go through a bowl quicker using a higher temp. So efficiency requires some discipline in the vaping process, no matter what model you're using.
The LB and V-Tower may be available at similar pricing, but for most vaporists they're complementary models-kind of apple and orange. You can't really go wrong with the LB. Most people appreciate a stealth portable, no matter what they end up with for home use. And some are happy using nothing but that, especially if you add the power adapter. I personally don't care for the V-Tower, since the bowl is large and vapor density isn't the best. You can improve that aspect by loading the elbow screen instead of the bowl, but I'd rather have something like the DBV. The V-Tower would only tempt me if $ were an issue, since you can get one on eBay for about $100, and best auction prices on the DBV are around $160-170. I'd still wait and save for the DBV though. I think it's worth the extra $.