Both are fully capable of providing print-on-demand fulfillment for WooCommerce (as well as Shopify).

Printful is growing quickly and has more product options. They typically have better deliver time, though Printify often has better pricing.

It depends a bit on what types of products you plan to offer. Both allow merchants to sign up for free, so you can see pricing, available products, and product creation methods.

In addition to these two, there are a number of other print-on-demand platforms. Many are alike, but there are some unique differences regarding products offered, shipping policies, etc.

I publish POD Weekly, a blog and newsletter for print-on-demand sellers so I follow the industry closely. [more here: https://merchreadydesigns.com/blog/ ]

Feel free to schedule a call with me if you have any other questions regarding print-on-demand ecommerce!