What mod you buy should depend on what's important to you. Such as:
Battery life between charges: Do you need something that lasts as long as your eGo between charges? If so, you're going to want a mod that takes batteries with at least 750mAh.
Voltage: Are you happy with your current voltage? If you are, you may only need to purchase a mod that runs a true 3.7v battery. If you'd like more heat and vapor, you might want to look into a higher voltage mod or perhaps an adjustable voltage mod or even a mod that allows you to change voltage with just a change of batteries. Example: There are some mods that allow the use of a single 14500 3.7v 900mAh battery OR two stacked 3v batteries to vape at 6v. One mod, two voltage choices depending on batteries used.
Size: Does size matter?
Cost: What would you like to spend on your new mod?
There are several things to consider. And there are so many mods to choose from...so the more you can pin point what's truly important to you, the easier it will be to decide which one you'd like to buy. After lots of trial an error I ended up with a very small 3.7v device that takes 1200mAh batteries to take out with me (Madvapes Roughstack) and a fairly large 5v mod that takes the same batteries (very nice to only have one type of batts to deal with I must say) for at home (Aceofvapes Golddigger). The battery life was very important to me and also the "toughness" of the mod (I drop things). I run LR cartos on the 3.7 and regular resistance cartos on the 5v and I love them both very much. So, I strongly suggest that you figure out what you truly need from your mod and then narrow it down to the ones that fit those needs. It will help.
