There's not a “best fax service” in general; it depends on what you're looking for. Here are some factors to consider:

1. How frequently do you fax? This is the most important thing to consider when choosing an internet fax service. Some services charge you by the page while others give you a monthly allotment of fax pages. If you are a heavy faxer you should consider paying a higher monthly fee in return for getting several hundred pages of faxes (fax out and fax in) each month for free. If you are an occasional faxer you should consider services with low monthly fees and per-page rates.

2. Do you need a toll-free number? Most fax services give you the option of using a toll free fax number. You can include this number on your business card to convey a since of professionalism. But some people would prefer a local fax number. Ironically, it's sometimes harder to find an internet fax service that offers local numbers in your area than one that offers free toll free numbers. This is an important distinction that I discuss at Fax.info.

3. How do you want to receive your faxes? My preferred method is to receive a .pdf attachment in my email. But some fax services require you to download proprietary software to view your faxes. You should also consider if you want to be able to access your faxes online. Some services offer online storage and retrieval; others don't.

4. Do you need just one fax number? If you work in an office environment you might need to select an online fax service that offers multiple fax numbers for your company.

These are just four of the important considerations to think about when choosing an internet fax service. Good luck!