An Aspire CF Mod (pocket-friendly, tube shaped, takes a single 18650 battery, no settings to fuss with, etc.) would be a good one for you, IMO. You can use a huge variety of tanks on it that take factory drop-in coils, too. The mods are inexpensive, too, (especially with some Googling to find the lower prices), so it wouldn't cost much to get 2, so you have a back-up one. The last ones I bought were marked down to less than $10 each.
After quickly checking out 4 websites that carry them in the US...this 1 has by far the lowest price at $14.00 each + S/H. Other places were all $20 and up for the same thing! (I've purchased things from them several times, and they're a good vendor to deal with.) They have only black, and they do have
at least 2 in stock right now.
Aspire CF MOD 18650
You'd also need a few 18650 batteries and a charger if you don't already have them. There are several good places to get them, so they're definitely authentic batteries (ie. rtdvapor.com, batterybro.com, illumn.com, imrbatteries.com, liionwholesale.com, orbtronic.com, etc.). I've gotten most of my Samsung INR18650-25R 2500mAh batteries from lightningvapes.com when they have their sales. They're authentic and at a
really great price then. Their S/H for 6 was less than $5.00, too! They also carry chargers. You can use the coupon code LV15 though, at any time on their website...to get 15% off your total order.