Now, I don't really have advice regarding what we here call "cig-a-likes" because while they are stylish and functional...I find them to be impractical. One very important thing that you MUST know about batteries when it comes to voltage drop or running time is what is called Milliamp Hours (mAh). In case you don't know, mAh is going to be the #1 factor that determines just how long a battery is going to last you. There are several other factors as well (such as coil resistance, voltage/wattage, dual-coil/single-coil, etc.) But seeing as how you are still a novice in the vaping community, we'll ignore such factors as you probably have no control over them.
Looking at the G6 Starter Kit offered from Halo, they really don't mention a mAh. Your typical cig-a-like (ecig that looks like an analog) is going to offer between 175-350 mAh which may last a light vaper an hour or two. A heavy vaper would probably get about 5-10 minutes out of this, if that. Now keep those numbers in mind while I try to take you through this.
Next on our list is the Triton VV offered by Halo. This is quite the step up from the previously mentioned G6 as it offers between 400-1300 mAh. As you start out and advance in your vaping experience, a decent 1300 mAh battery could potentially last you all day! But again keep in mind of those hidden factors I mentioned earlier. This battery looks like it has the 808 threads you mentioned as well as standard eGo threads. Not too bad of a choice, but your options of toppers are still limited should you decide to experiment in the future.
Now let's look at that Mig Cig 140. I have never personally heard of this battery, and I can once again see why. I would consider this the 100's of cig-a-likes. From what I can tell, it's the same thing but just a little bit longer to hold slightly more charge. This battery actually states that it offers 380 mAh - a bit more than the G6, but still quite a bit less then the Triton VV. For a light vaper, this might last 3-4 hours. For us heavy vapers...well, we inhale our juices instead of sucking on them - it might last an hour, at most.
Again, I don't really have any experience with cig-a-likes as I've moved quite far past them. But I will not ignore the fact that there still people who like them. Looking at the batteries you have listed; if you like the Triton VV, it is by far a step up from the other two. Once you experience the joys of controlling your own vape with Variable Voltage that lasts longer than an analog itself, you will never look back.
Also, I know you said you're not quite ready to move on to mods just yet - but trust me, you'll get over the box-like shape of a solid device like the MVP 2 in no time once you learn all it has to offer. For ~$40, this device has a mAh rating over 2000 which will last even the most heavy of vapers a good, guaranteed day or two. Once you're ready to make the jump, you know where to find us!
