Ethernet is a reliable standard for Internet connectivity. If you don't need Wireless (and don't want the headache of wireless either), then Ethernet can be a very good option.
No antennas, no SSIDs, no passwords, plug it in and forget about it.
While there are a few Feathers that have built-in 'Ethernet support' they all need a PHY interface anyways and it's about the same price as the W5500 chipset we use. So we just went with this, which is a well-known (or, at least, infamous) chipset. And, yes, you can use it with our WiFi Feathers to create a Feather with dual-connectivity options (or a very slow and silly WiFi bridge)
This Wing uses the SPI pins and a CS pin, you can cut the jumper to re-assign the CS pin. You can use with other SPI-based wings (displays, music, radio, datalogging, etc) just make sure there's no pin conflict for the CS pin.
This Wing does not support active Power-over-Ethernet (PoE), but you can easily hook up a passive PoE configuration with a passive injector, a 5V power adapter, and a 2.1mm to MicroUSB cable. See the tutorial page for more details