I've used them all, and they all have their place I guess.
ChatGPT is far and away my favorite for quick questions you'd ask the genius coworker next to you. For me, nothing else even comes close wrt speed and accuracy. So for that, I'd gladly pay.
Don't get me wrong, Claude is a marvel and Deepseek punches above its weight, but neither compare with stuff like 'write me a sql query that does these 30 things as efficiently as possible.'. ChatGPT will output an answer with explanations for each line by the time Claude inevitably times out...again.
Why would you pay if you can use a competitor for free?