Ego is an excellent Intro device for the NEW vapor. Simple, minimal maintenance and reasonably priced.
CE4 is good for 1 juice and can be rinsed, left days to dry and reused.
CE5 is better, serviceable and can be cleaned/dried/refilled in 5 minutes.
Twist/spinners are nice once you have a handle on vaping. Finding a good vaping temperature allows for better overall flavor.
Vamo/eVic/Provari/etc. etc. etc. are all good fun devices that can do much for the more advanced Vapor. None are needed for someone starting out. All require more investment and come with a learning curve for best performance.
As far as strength - What do you smoke? If you smoke full flavor of a brand that is strong 24 - 36mg (2.4% - 3.6%) is necessary. Lights usually equates to 12 - 24mg (again, depending on brand). Some here will tell you how much you smoke matters, I don't agree. If you get the right strength you will be able to vape the same way you currently smoke. But most people do find they vape more than they smoked since they can do it in places and at times they couldn't smoke.
Not sure why people make these assumptions. Nic intake will be on a VERY PERSONAL LEVEL and NOT dictated by smoking habit.
i.e. I Smoked Marlboro reds 45 years but started Vaping at 18mg and after upgrading to better gear dropped to 12mg without any withdrawal or stress issues. A friend that smoked lights is still vaping 18mg. another that is a long time heavy smoker started at 24mg, jumped to 36mg then after a few months decided it was to much and is now down to 18mg.
Buy in small samples and find what works best for YOU.