I have had one swollen tonsil for 7 years. an ent said i could have it removed (could be cancerous?) or get a ct scan. what is the best option?

Depends: As a radiologist I would pick CT. The main reason is this. See what you are operating on. The CT may offer in site into why one is larger than the other. It will see if there is a peri tonsil abscess for example. Other possibilities exist. Look for stones. I believe that operating without a CT is shall we say not necessarily a good idea.