For someone just getting started, the standard 510 (that's the type of connection between the battery and the atty or carto) look the most like a cigarette, but the batteries are only good for an hour or so per charge. The KR808 is also popular and lots of options for those as well.
If looks aren't the most important, a slight increase in the diameter like the Riva or Ego (also 510 connection) will give you 4-6 hours per charge. The Go-Go is excellent if you want "fiddle free"
vaping, but its threads are proprietary (don't work with anything else). Its battery is good for 12-24 hours, and it holds 3ml of juice (about what the average person vapes in a day)
Any of those are a good place to start, but read up on them and ask LOTS of questions, it can save you money in the long run and folks here are happy to help. There's lots of other "good" ones, but a lot depends on your preferences, budget, etc.