I also love my LB, but the tastes from a whip vape are just so much smoother, it's just a way more enjoyable experience for me.
Really, as long as you get anything that uses convection (stream of hot air drawn over herb rather than direct physical heat transfer) you'll be experiencing much smoother and better tasting hits than the LB will ever give, since loads will be much more evenly vaped. The Purple Days style vapes use convection, as do the whip vapes like the silver surfer, da buddha, vapor bros and others, so you really can't go wrong with either style.
The PD-style vapes are supposed to be efficient vapes, and probably are for all i know, but if i take a LB trench-load amount and put it in my SSV, i get just as many hits, only they taste and feel better on the throat. So i can't really say theres any great loss in efficiency, and i really am 100% satisfied with it, (unlike my dbv, because i ended up not liking the ground glass connection).
I personally like to have a variable temp, just something with a knob, and a whip to help cool it down. I think vapes should have the power to combust if you crank them up (not that you should, thatd be stupid), so you can be sure that you're able to get the full range of active ingredients from your herbs. I know the PD vapes are set-temp, and i've seen some ppls abv and it didnt look very well done IMO, and there are some ppl who really need that higher-temp vapor to get the best effect for them. I also think it would be more enjoyable to pass a whip rather than a pd/wdz/mz.
Just read what everyone says here and take it all into consideration and make your decision. I really recommend reading some in-depth reviews and doing some searching on youtube once you get it narrowed down a bit. Try to find videos of people loading and using (and cleaning) the vapes and see which looks most comfortable to use for you.