I'm not really qualified to speak on this topic, since I haven't actually begin my "four-wheeled lifestyle" yet, but the phrase "for now" strikes me as an important one. No one vehicle does everything equally well, so as your lifestyle goals change, so will your rig.
In my case, I plan to spend the first couple of years zipping all over the U.S. making business connections and finding new clients for my (freelance) career, which means lots of driving and days spent out and about instead of living in the vehicle all day. So for me, a minivan is probably the most sensible option -- like those "capsule hotels" Japanese people squeeze themselves into at night when they've missed the last bus home. I have a feeling this class of vehicle will also be easier for an inexperienced vandweller as far as maintenance, repair costs, parking, stealth boondocking etc.
Once I've done all the cross-country business building I can reasonably do, I may want to stay put most of the time. At that point, I'll scale up to a cargo or conversion van of some sort and park the thing on BLM land, etc. MPG won't be a big deal at that point, so I'll focus on comfort.
