A good Arborist shouldn't be hard to find. The CAA doesn't recommend any one company, but can help you find one.
Finding An Arborist
A few tips:
An Arborist should be Certified with the International Society of Arboriculture
The company should be insured with both workmans compensation insurance and general liability
A good Arborist should understand your tree from the tip top down to the roots and soil
We have links to company websites of our members on our membership page. Below are a few other resources to help find the right Arborist for just about any job.
The ISA is the largest certification organization for trees and Arborists. They offer a wide variety of certifications in everything from climbing to assessing the risk a tree posses. Any company should be familiar with the ISA and preferably Certified.
The TCIA has another tool to help find the right tree company. The TCIA has a heavy focus on safety and training standards and any company that is TCIA accredited knows what they are doing and takes safety seriously.
Most people never need a Consulting Arborist. ASCA is good for situations where there's a good chance a lawyer will be involved. If someone is suing you about a tree ASCA is a good resource. If you need to have a tree pruned go with the ISA or TCIA above.