I'll offer my opinion, now that I've officially used four different vaporizers.
Yes, they all give vapor, but they do not all extract the same.
If you are looking for something with a bigger bowl, you may be looking for better extraction. With a log vape, and now with the EVO, I am getting MORE vapor, and more medicated, using about 0.1 or a bit less.
My prior portable gave good hits, but not the full extraction, and I was never as medicated, using the very same amount.
What is your need? From reading, my impression is that the Sub is going to give you huge, fast, THC prominent hits, and the rest of the herbal goodness is reclaimed, and then hit as a concentrate. If you are looking for high THC, that might be what you are after.
A log vape will give you lots of vapor, and decent economy, for really nice extraction. Think a more balanced high, and a bit more of the CBD/CBN. Log vapes have a real advantage in that they are always waiting, you can bring to it straight glass stems, or water tools, invert on a bong, etc.
The EVO seems to give a full extraction of the goodies, for me, at the same settings as my previous vape, I seem to get way more medicated and body relief, with a less "giddy" head. The ABV is also very evenly browned. I use about the same amount as I have in all my other vapes, and I am getting way more results that last longer.
If you are planning to hit it often, and want to switch things up a bit, I'd go with a log vape. If you are going to use it less frequently, like once or twice a day, or even just maybe a few times a week, you might look for the faster heatup time of something like the Sub or EVO - or, maybe even the Herbalizer.
Best advice I have for you is pick two or three that sound interesting, and then read the last 10 pages or so of each main thread. If any sound good, then go back further, and look for videos, specs, and reviews.