If you want to talk about dialogue, scientific accuracy and the like, sure, you could use plenty of other writers.
If you asked me, though, what writer i'd like to sit down with and ask tons of questions, it's Stan Lee. Not just because he created my favourite character (he did), but he was the gamechanger.
I actually want to be a comic book writer one day, and my absolute number one rule when I sit down to write a script is: These are people first, and heroes/villains second. Stan Lee is the reason for that.
His imagination when coming up with new characters, not to mention twisting timeless themes in to longevity, makes him, imo, the best comic book writer.
He is to writers what Superman is to superheroes, to me.
Stan Lee blew up the genre and added pathos and humanization to it more so than the others who came before him. He was more interested about the people behind the masks and costumes and made them infinitely more relatable than they had been before. If you were to remove any of the other above names from the genre, you'd be missing out on some great works of art. But if you removed Stan Lee, the entire genre would be radically different to the point where it wouldn't even be recognizable.
c'mon, don't be so static. compare comics to any other medium. do you think that alexander pope is the best writer of all time? do you believe that the marx brothers are the best comedians of all time? that elvis is the best rock n roller of all time? that orson welles is the best filmmaker of all time?
all brilliant, all trailblazers, all since surpassed. stan lee is not the best comic book writer of all time.
Lots of confusion. Need to set what you mean by best...
Best for their era?
Best from a subjective, personal standpoint?
Best in terms of influence and affect on the industry?
There are likely more ways to define it. Those are a few obvious ones. Stan likely takes the last, and handily. The others, especially the second, will vary person to person. Mine would be Ellis.
From what I understand, Stan Lee's actual contributions to developing early Marvel characters and storylines, while very important, have been overstated, and much more credit than is usually given is owed to Jack Kirby, who was his partner while they created the Marvel Universe.
I even heard once (this is probably apocryphal) that Jack Kirby created the characters, the designs, and the actual storylines, while Stan Lee was just the guy who came up with the basic plots and the filled the dialogue balloons.
__________________
“Where the longleaf pines are whispering
to him who loved them so.
Where the faint murmurs now dwindling
echo o’er tide and shore."
-A Grave Epitaph in Santa Rosa County, Florida; I wish I could remember the man's name.
Best based on proficiency in writing/storytelling assessed by today's standards.
I was under the impression this was usually assumed when not listing criteria and saying "best of all time" and it seems everyone else understood that clearly enough.
Jeff Lemire's great but I've found him to be a bit more hit or miss then someone like say, Scott Snyder. Animal Man has been unbelievable as has been his creator owned stuff, and most of his other DC stuff been great but his work on Frankenstein was just plain bad imo.