Hello Again!
A lot of folks may not share their "favorite" companies as many of us have spent a lot of time finding our niches in this industry and, when push comes to shove, we are all competitors. Start with the list linked at the bottom of this page and sign up for as many companies as you can - if you do a few every day, you'll have quite a list a month from now. I'm with upwards of 130 MSC's, for instance. You'll also find that different companies specialize in different types of shops and each has its own personality. As a result, everybody's "favorites" are different.
If you read the forum, you'll get a sense of some of the companies but, otherwise, you really do need to sign up for them yourself and explore them on your own.
Hard work builds character and homework is good for your soul.