It's hard to definitively say which polymer clay brand is the *most* popular globally, as popularity varies by region and individual preferences. However, some of the most well-known and widely used brands include:

* Fimo: This is a classic brand with a wide range of colors and finishes, known for its durability and ease of use.

* Sculpey: Another very popular brand with a wide variety of clays, including Sculpey III (the original and most versatile), Sculpey Premo (for stronger, more durable pieces), and Sculpey Souffle (for lightweight and flexible creations).

* Cernit: Known for its vibrant colors and its ability to be baked at lower temperatures, making it a popular choice for beginners.

* Kato Polyclay: Offers a unique range of colors and finishes, including pearlescent, metallic, and translucent options.

Other popular brands worth considering:

* PMC: Known for its high-quality clays, including PMC3 (for fine detail work) and PMC+ (for larger and more intricate pieces).

* Premo: A more recent brand with a focus on providing high-quality clays at affordable prices.

* Cosclay: A brand specifically designed for cosplay and character sculpting.

The best brand for you will depend on your individual needs and preferences. Consider factors like:

* Color range: Some brands offer a wider selection of colors than others.

* Durability: Some clays are more durable than others, making them better suited for certain projects.

* Ease of use: Some clays are easier to work with than others, particularly for beginners.

* Price: Prices vary by brand and type of clay.

Ultimately, the best way to determine the most popular brand for you is to try out different brands and see which one you prefer.