If you had to pick one. For someone who just wants to hear his story and know more about him, which would you buy?
Learn his Torah, you'll find something that isn't in any biography
honestly, I wouldn't outright recommend any of the three, though all are an interesting read overall.
I found telushkin's to be the most enjoyable one to read
Same is true for all his books, at least the ones I read.
In style, your source is probably right, but telushkin had access to much more information (documents etc.) than Miller.
I also think telushkin's book went through much more vetting to ensure the accuracy of everything.
Vetted? I'm afraid the people who provided him with documents were selective/biased, same with their "checking for accuracy". But Friedman, Berger, Deutsch etc. are at least equally biased.