What is the best visa option for working in Thailand if I currently have no job?

CoE is old school, it is now called a Thailand pass.

You can not get a tourist visa on arrival as this is a mix of different ways to enter Thailand.

Or you apply before you travel for a Tourist Visa which gives you 60 days on entry or you come without visa and use the 30 day Visa Exempt Scheme.

Both one time possible to extend with 30 days.

Best option is to let your future employer send the documents to apply for a Non Immigrant B, than come to Thailand, pick up your work permit and go to work.

Whether the application for in-country Non-B (based on employment) from the entry stamp on a SETV or visa-exempt is possible or not? It is possible.

But it totally depends on your future employer and the local immigration office they deal with IF you really can apply for in-country Non-B. So before you know who is your employer, the answer is totally UNKNOWN.

You will have only 89days max with SETV entry + tourism extension. If you want to enter Thailand on a Tourism basis and you want to get Non-B inside the country, you need to complete these within the first 74days at the longest (because there is a requirement you need to have a certain number of remaining days with your current stamp), such as finding the employer who can go on the in-country process and get a contract to be employed by them.

There is no option for you to stay for a year based on tourism unless you get Thailand Elite (but with that, you cannot work).