My honest pick would be the iPV Mini and an 18650 battery.
A lot of people say to go with the iStick or MVP however this great little mod isn't much more and opens you up to more options if you ever wanted them. Not everybody is into Sub-Ohming but this device is capable and with the Kanger Sub Tank and Aspire Atlantis, it's easier then ever and becoming much more popular. And even if you never get into that. It will still work well with normal tanks.
It's more comfortable to hold since its made to fit in your hand and you don't have to throw it away like the MVP or iStick if the battery goes bad since the battery isnt built in. It would cost you more to replace a battery on an iStick then the device even costs.
Product Specifications:
Dimensions: 94mm x 40mm x 23mm
Accommodates a single 18650 sized battery
Output voltage: 3.0 - 8.0V
Atty resistance range: .5 - 3.0 ohm
Spring loaded top pin
Visual operating system
Low voltage protection
Low resistance protection
High input voltage warning
Output short circuit protection
Reverse battery protection
USB charging