I know everyone has their own problems, but my first choice, Eleaf, is not only famous, but also has very few failures, many stores carry them, and I think the pricing is quite accurate, so I recommend it especially for those who are just starting out and don't know what to buy.
How to choose
Famous e-cigarette manufacturers
I think it is better to choose a famous manufacturer.
Many vape manufacturers are from overseas, and many of them are quite crude, but if you choose a famous manufacturer, you can be sure that you will not find anything that bad.
If you know how to use it well, it's fine, but many instructions are not easy to understand, but if someone introduces it on the Internet, you don't need an instruction manual.
Voltage adjustment
If you can adjust the voltage, you can make the smoke the way you like it.
Some manufacturers have a voltage adjustment function in almost all of their models, so even if you buy an inexpensive model, you may not be disappointed.
I choose a model from a manufacturer that has the functions I want.
Price
Cheap manufacturers are very cheap, and expensive ones are very expensive.
Cheap ones are not all bad, but there are many lousy ones.
I have the impression that many well-known makers have good products even if they are inexpensive.
On the other hand, there are some models and manufacturers that I don't understand why they are so expensive.
It is not an excuse if they are expensive.
Ease of purchase
Recently, you can buy e-cigarettes at Don Quijote and convenience stores, but I think the number is still small.
I often buy on the Internet, such as Rakuten, but sometimes I cannot find the vape manufacturer I want to buy anywhere, but I think the best thing is to have no trouble, so I think it is better to buy something that is sold everywhere.
Manufacturers that are less prone to breakdowns or malfunctioning parts are easy to get.
My main product has never broken down in 7 years, but it still breaks down when it breaks down.
There are some manufacturers that I think have fewer breakdowns than others, and there are also some manufacturers that I have an image of that break easily, but the manufacturers that have many parts that are easy to buy and replaceable for repairing broken parts are probably the most famous manufacturers.
Merits and demerits
Advantages

• Hard to break
• Less likely to leak
• Voltage can be adjusted.
• Strong battery

Disadvantages

• High price
• Not good for something that can be purchased in a store.
• Heavy
• Some products are not well made.

Recommended e-cigarette manufacturers
JUUL Labs
JUUL Labs is an American manufacturer that was established in 2017 and has grown rapidly since then. JUUL is famous for its pot-type e-cigarettes, which have captured 75% of the U.S. e-cigarette market share.
With its stylish design, JUUL Labs is beginning to attract attention in Japan and the rest of the world. They are especially popular among women.
Rockville Co.
Rockville Co., Ltd. is a manufacturer of e-cigarettes for Japanese people based on the concept of "the world's most delicious and healthy e-cigarette.
The company's products are designed by Nicola Formichetti, a world-renowned fashion designer, and are very stylish, fashionable, and popular among young people.
There are two brands of e-cigarettes: Nicoress, which is nicotine-free, and Vitaful, which is tar-free as well as nicotine-free.
Especially, Vitaful is available in disposable and cartridge types that do not require liquid disposal, so even beginners can use it easily.
Joytec
Joytec is a Chinese manufacturer with a long history, established in 2007, and is popular for its wide variety of variations and stylish designs.
We recommend the eGoAIO, which is compact disposable vape but offers a strong flavor. There is also the Delta II if you want to enjoy explosive smoking, and the CUBIS Pro if you are concerned about liquid leakage.
Eleaf
Eleaf is a manufacturer with a wide variety of e-cigarettes, including the iStickPico series and elven.
Choose the one with a long-lasting charge if you use it frequently, or the new pod type if you want to enjoy flavors, depending on your preference.
Although it is a Chinese manufacturer, its high quality is also popular. There are products for beginners as well as for advanced users.
SMOK
SMOK is a product of Chinese manufacturer IVPS Technology. It is highly functional and uses advanced technology.
It is popular among those who want to smoke explosively because the smoke volume can be adjusted, and everyone uses it, whether they are beginners or advanced users. It is also stylish in appearance and does not leak, so you can always keep it in your pocket.
INNOKIN
INNOKIN is a popular American manufacturer. It has an after-sales service office and repair center in California, and its factory is located in China. The simple system of colors is easy for anyone to use. Warming the liquid at a low temperature enhances the flavor of the liquid. The manufacturer is well known for its delicious taste.