As noted above, be aware that if a person is posting here they are not driving. Thus, the posts here may tip toward the negative because the people who would say very positive things are too busy driving to read the forums.
As for how much money people make, I think this depends on two things: luck and how long you want to stay out. Based upon these two variables it is hard to really say how much a given truck and driver will make because different people have different comfort levels with how long they want to stay out and how lucky they are.
As for the best companies, the question is "best for what?" Again, different people have different ideas of what a good company is, which means different people will say different companies are the best. I am leased to Con Way Now and I am very pleased with the way they do business. One practice in particular that I like is that they will work to set up relays on long loads so that a solo like me can get a piece of it rather than having to wait for something that can be done in 11 hours. A team wouldn't give an oink about this practice.
The ideal company also depends on where you live. If you live outside a company's freight lanes, it probably won'y be a good fit for you.
As for advising people not to get into the business, I think this is a pretty neat way to make a living and a pretty neat way to spend your time on this earth. A lot more challenging than a person might imagine.
Also a lot more frustrating at times. Just wait until you decide to take your straight truck off road "just to see what it's like" and get stuck and have to spend several hours digging it out and enlisting mutliple 4 wheel drives to pull you free. I had a "friend" that this happened to.