Despite its hokey name, myfax.com seems a good service. Jfax/j2 gave good service when I used it some years ago; it also received voice mails and sent them as emails, very nice to be able to save them, rename them, etc.

What is recently terrible is 'faxitnice'. No response to questions, and kept billing my credit card after I cancelled!

Efax was a nuisance, using its own coding. Myfax uses tif or something simple iirc.