If you're a startup beginner, mainly doing custom small gifts like phone cases, then choose a small-format printer, such as A3 size, 4050 size, 6090 size, and similar models. These types of machines are very flexible, have a small footprint, require low investment, and pay for themselves quickly.
If you're in the advertising, sign making, or plastic product printing business, and you often need to print display boards and large-quantity orders, then you should choose a large-format industrial model, such as 2.5m × 1.3m.
If you're going a step further — planning to do whole-home customization or building material printing (these extra-large materials) — then don't hesitate and go directly for a 2.5m × 3.3m machine. These industrial machines are not only stable and fast, but also durable.
To sum it up in three sentences: For small-scale, low-volume work, use a desktop printer. For advertising and sign processing, go with large-format. For bulk building materials, go with extra-large format.