I have a Thomson post on all three of my bikes and I will tell you why.
1) Strong - I bent three posts before I was recommended a Thomson. I balked at the price, but I have never bent a post since.
2) Aesthetics - They look pretty and have an excellent adjustment mechanism.
3) Customer Service - I didn't tighten the adjuster bolts before a race and lost one bolt during the race. Fortunately I did not lose anything else. I called Thomson the following Monday and they sent me not one, but two new bolt assemblies because I probably damaged the remaining bolt. THEY DID THIS FOR FREE AND I HAD THEM FOR THE NEXT WEEKEND. You can buy those same bolts for $6 at a lot of shops.
You can't beat that.