OaklandCA:
i want to know the pros and cons of various vaporizers in order of importance to me.
1.) vapor and taste production ( i assume these are linked but maybe not.)
Vapor is a result of the combination of the voltage of the battery (not the stated voltage but the working voltage). A 510 oem batt can put out 3.0-3.2v. A Tornado/eGo a bit more. A 14500 batt in mods will get you 3.7+Volts. And you have 5, 6, 7.2V mods.
Combine that with the ohm rating of the atomizers and you'll get variied levels of vaporization.
The regular Joye 510 atty has a lower ohm rating and runs warmer than any other atty and will hence produce more vapor given that the voltage is constant.
Some flavors are enhanced by heat, some flavors are diminished by it. Stronger flavors usually respond favorably. Lighter flavors not so good. Strong flavors don't taste the same on a 901 as they do on a 510 and fruit/berry flavors do better on an 801 or 901 than on the 510, imho, and this is a fairly common experience. ymmv, of course.
2.) longevity
As far as long between chargers the mAh rating is a good measure and even though the ratings may be exaggerated, they are consistent in their exaggeration - I figure 100mAh = about 1 hour. So a 900mAh batt can last 9 hours, ymmv....
If you mean battery life, that's in the number of charges that a batt will take and that is usually in the specs. Don't have a chart to show you, sorry.
3.) ease of connection with reliable and standard batter options (510 preferred)
Never had a problem with the 510. There are adapters for almost all attys now. Some cartomizers don't work with some cartomizer type batteries but forget exactly which models - green cig or green smoke... I think green smoke is the one that isn't compatible with others.
3.) low maintenance
I find using the 3.7V at peak voltage with mods tends to self clean attys. The less cleaning the better. I didn't used to think that, but I only clean now if there is a performance drop.
4.) price
The Joye 510 starter kit a cignot is one of the best deals out there. 2 full ecigs (not the case with all 'starter kits' and a regular wall charger - again, sometimes you only get a usb charger), charger, cartridges and the choice of colors in LED and batt type - get the manual type

Although the Joye 510 auto is one of the better ones - no timeouts or cutoffs.
If you get that the best price to a 3.7peak volt mod is to make one yourself - nicostick or get a Bartleby.
Not ready for that but want more battery life - Tornado/eGo.
Want to try cartomizers? V4L or get an adapter for the 510 to run cartomizers.
Like the lighter flavors -berries/fruits/vanilla/candy flavors - get 901 or 801 - 801 has a huge cartridge. Try a Joye Stick V3....