If you are going for overseas transportation, the research and verification process would be tougher. Here, it is best to go for a domestic based company for ensuring satisfaction. The foreign companies may offer cheap rates but verifying the details of such companies would be hard.
And to make it worse, if any problem occurs, it would be harder to resolve. If the company is unfamiliar to you, confirm the reputation with the Better Business Bureau and see if any complaints has been lodged. Leave off any company with no necessary license or insurance information. It is best to take recommendations from other experienced customers.