Tor is still traceable by professionals, however if you are remaining anonymous from general bitcoin users, then of course this is always a good step.
But, bitcoin is pretty anonymous anyway, they won't know your name, unless you are using a website which can track your ip and get information from any websites you have signed up with your real name.
If you are not doing anything illegal then there is no need to go these extra steps unless you want to use sites which take note of your ip addres.
But, even then some sites will not allow you to buy from a tor network because of too many ip changes.
So, it depends on what you want to do, if you can afford a VPN service.
then this is the best option by far.