Which is better, a trademark wordmark or a logo trademark?

It depends upon the Company's preference and the self coined word.

Logotrademark is safer as cannot be imitated.

What are the facts? What is the context?

Both are equally beneficial and it depends on the trademark. For e.g. if you want to focus on the name, then you should go for a word mark but if you have a different pattern in which the trademark is designed then you should go for a logo. Further clarifying please refer to the below logo/device mark of H & M.

Here, H & M has been written in a different way or manner and that needs to be protected, hence it has to be applied as a logo/device mark.

You can read the process in detail at Procedure to register a Trademark in India