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You can use the search function to find out what brands are popular as this is a regularly asked question. We all have our favourites so there's no definitive answer as it is definitely down to personal choice but a bit of advice I would give you in view of recent reports would be to stick with brands produced in the EU or USA as products made in China do not follow the same regulations with regard to ingredients. Unfortunately a lot of the newer popular brands that people are raving about fall into this category.
Also, use the complete system, i.e. Base coat, colour, top coat and lamp etc.
To be honest it's a bit of a minefield out there right now, with the increase of allergies occurring amongst so many nail techs. You're in the good position of being new to the industry, so making the right choice now and ensuring you work safely and cleanly should stand you in good stead for a long career in the industry.
Have you looked at Ikon.iq products? They are hypoallergenic and HEMA free and offer the full package, including training. Definitely worth looking at.