Well, for starters can you tell me what kind of battery life are you interested in? And does it have to be big or small or does size matter?
I would suggest getting an aspire nautilus mini for a topper if you want something smaller - you can control your air flow to make a tighter or looser draw - it produces very good taste and vapor - it's easy peasy to look after and change out coils. There is also a regular size nautilus which is quite big but it performs just as well and holds up to 5mls of e-liquid.
For batteries - if you want to start with something a little smaller to go with the mini nautilus - then you want to get a vv ego type battery, whether that would be an ego twist or a vision spinner 1300mah. This way you can dial the voltage you need to get a great vape.
Something a little bigger but with much longer battery life is the Innokin MVP. It's a box mod - 2600 mah so it will last you a good length of time. MVP's are solid performers.
If you want to get into a regulated mod with removable batteries - well - there are many and they come in different sizes so you can tailor what you want to what you need. What I have suggested though, is a good place to start.
I wish you luck and hope you find the set up that will get you back to vaping.
