if you are looking for something easy and fast - bug free, , and working for certain looking into ARM s seems the best choice, if you want to go cheaper - not sure about this - using modules might be very good, but if you still want to go cheaper, I would suggest looking into 18F series, a lot of coding must be done if you want something bug free.
If you have a favorite microcontroller that doesn't have ethernet, you could attach a Lantronix Xport-Pro to it. Not cheap, but has a lot of capabilities.