TL;DR
If you live in North America: Perler. If you live in Europe or Japan: Hama. If you live in mainland China: choose the code system your seller uses, usually MARD, Artkal or COCO 291. Ironing behaviour is close across comparable bead sizes; the practical choice is local stock, bead size and whether the exported codes match your supplies.
Palette breadth
Artkal has the broadest catalogue at 300+ colours. MARD 291 and COCO 291 sit in the high-detail Chinese small-bead workflow. Perler is broad around 150 colours, while Hama is smaller but easier to shop. For colour lookup, /colors lists each bundled palette with hex codes and nearest equivalents.
Ironing temperature & timing
Comparable midi brands usually fuse cleanly between 150–180°C with a household iron and baking paper. Mini-bead systems such as COCO need lighter pressure and more care because the pieces are smaller. Always test on spare beads first.
Cross-brand mixing
You CAN mix brands in a single pattern, but watch out: bead pitches and heights vary by ~0.1–0.2mm between brands, which becomes visible after fusing. If you must mix, group adjacent beads from the same brand. Bitbead's per-colour breakdown lets you spot-check whether a pattern uses just one brand.