Your local garden centre sells a range of tool brands. It’s a question of personal preference of course but I would plea that you buy the best tools you can afford.
Secateurs are the gardener’s equivalent of a soldier’s rifle. Professional gardeners who know what they are doing have their secateurs in a holster which although can look posey, it’s a time-saver. Otherwise you’re there forever ferreting around looking for them on the ground.
The mow and blow guys with their 2 stroke machinery do not have secateurs to hand in a holster.
The secateur brand favoured by top gardeners is Felco. These are the red, heavy metal range you will see sold under lock and key due to their high price tag. Personally I prefer the Japanese supplier Niwaki. And always buy them with a sharpening stone.
However, I recently bought a much lower priced standby pair by Wilkinson Sword. They are amazingly sharp and probably going to stay that way for a long while. I would highly recommend these to those who don’t share the same enthusiasm for gardening as a professional and have an eye to price.
Tools rule: always keep them sharp and keep them clean. Really clean. I have seen the devastation visited on prized box topiary by the operative who failed to clean his blades properly.