Choosing the “right” brand is a very personal thing but the best advice I can give is to firstly draw up a list of “real” brands that actually produce their gel products themselves, rather than buying in and private labelling, which is what so many of these new “brands” are doing. By buying from a brand that actually produce their own products and have their own chemist you can be reassured that they have the full knowledge of what they are selling. Check that they have a tried and tested lamp for their system (and dint just recommend any lamp of a certain wattage will do. This is not the case and if they say it is, then they don’t understand the curing, so should be avoided!).
A good brand will also offer education and conversion courses and will be happy to answer any questions you ask.
Once you have done your research and drawn up a shortlist, it is then a good idea to trial them to see which works for you. But you will need a matching base coat, colour/s and top coat, so it’s definitely worth narrowing it down to 2 or 3 to stop it becoming too expensive!