As we've said, there are three main variants: electric, gas and coal/woodburning smokers.
The advantage of electric and gas is mainly the simplicity. Electric smokers basically work so that you turn it on, and then it takes care of itself. It keeps warm and feeds a new puck with smoke shavings when the time comes. Gas works in much the same way, but you usually need to refill smoke shavings yourself at regular intervals. Compared to electric smokers, an obvious advantage is that you are not dependent on an electrical outlet.
The classic charcoal/woodburning smoker grills are the ones that requires the most commitment. You need to monitor it to make sure that the temperature is right and that you have the right amount of smoke. In return, you also have great opportunities to vary and experiment between which wood you smoke with to bring out the best taste just for you. Many enthusiasts believe that the taste becomes superior in a classic smoker. Many classic smokers can also be used as a regular charcoal grill.
Think about what's most important to you. If you are looking for convenience, you should look at the electric or gas-powered variants, but if you want to experiment more and maybe try to pursue the perfect result, the classic models are a better option.
Don’t buy a smoker that is too small, if you choose between two sizes, take the larger one if you can and can afford it.
In the end, of course, it's also about the money. There are cheap smokers from 100–200 GBP and large ceramic smokers that keep the heat incredibly well for over 2,000 GBP. Let your needs and budget guide you to your choice.