Simple, good vapor production, ready parts availability, 2 piece -- KR808D-1 family. NHaler, vapor4life, and vaporsetc are all good, reputable, suppliers, fast shipping.
A basic kit, 2 batteries, charger, couple of initial cartos is $37 - $50. All 3 vendors have 10% off coupon codes I believe.
The standard length 808 battery is good for several hours, while the XL or Mega battery goes noticeably longer. A PCC is handy if you are away from power for extended periods (it's an on-the-go recharger), or pick up a cig lighter - USB adapter (with 2A output) and a passthrough, if you like to vape in the car a lot. A passthrough is just a connector with several foot cord, ends in a USB connector, lets you vape without using the PV battery.
Prefilled cartomizers (cartos) are widely available, while many do quickly get into filling or refilling their own (the vaporetc. kit comes with 5 blank cartos plus an initial small bottle of eliquid).
Top off your cartomizers periodically -- condom method is simple, some liquid in the rubber cap, slowly push the carto into it, blow through it to clear excess liquid, wipe the battery terminal with a tissue and put in on the battery. I carry little 6 ml bottles of liquid, and cartos, in tiny ziploc bags from Walmart -- works well to organize things.
The 808 standard battery, either manual or auto, is likely sufficient for a relatively light vaper, which you are, given a carto lasting close to 2 days. It, plus carto, is about the size of a 100 cig -- not too large/noticeable. The big battery Riva/eGo, or the 808 format G400, is cool, but not necessary for everyone -- I like to be able to hold a standard 808 in my mouth, hands free, for some things.
A straight 510 kit is also an option, though I prefer the 808's better hit (higher voltage for a given resistance atomizer), and longer battery life (more mAH = more run time between recharges).
You have multiple choices, any of them might well do for you.
Good luck!