Any genuinely good KW research tools

Soovle & Jaaxy, i have tried both of them & both are great.

Semrush or longtail pro is good for beginners. User interface both are easy to understand.

Thanks for everyone's reply! I've already checked out the majority of the suggestions. And, I will be doing my best to look into every one of those.
I usually provide content writing, but, to be fair, recently most of the real work for me has had to with SEO optimization, backlinks and reading stats.

Priceless info all around. Cheers!