I'd say Salvatore overall in writing style is a DIFFERENT writing style, but wouldn't say Tolkien or Hickman/Weiss were better.
How does one judge who is the better writer?
Active vs. passive tense?
In which case Salvatore is hands down better than Tolkien...
Backstory and the incorporation of literature and mythological elements?
In which case Tolkien is hands down the better writer...
The interesting thing about this is the matter of opinion.
Currently I think Tolkien will have a bigger impact on literature...which is how people get classics...either that which has a bigger impact on literature, statments about society, or popularity...
But I wouldn't say that defines who is a better writer...or not.
That instead is a matter of opinion.
Writers of Classics are hardly ever the best writers of their times...only the most noted...
Tolkien himself...of interest...or rather his books...were in obscurity in regards to popularity for years...and considered rather useless as they were childrens and young adult books (which is ironic considering the current views of them and the context they are put into with the movies).
In a counter to Tolkien one could always look at CS Lewis's fantasies for children as well (I'd put Tolkien for more of an older audience...but as stated, as started with the Hobbit, they were more directed for a youthful audience of the time...hence my parents and grandparents generations...or perhaps the arena in between when the books were written). CS Lewis ironically was considered the greater writer at the time overall...and Tolkien the one who wrote interesting but insignificant books (of course most fantasies back then were for children...looking at the context of the times. The closest to fantasy for adults in mainstream was...Science Fiction!).
CS Lewis also wrote many other books, which were considered adult in material...even though some of them were more fantasy in many ways.
It is only in the past years AFTER Tolkien's death that these books have started to be considered classics and gain popularity, and even, as akin to most fantasy, much of which has been inspired, intentionally or unintentionally, by Tolkien's Trilogy.
Of course, of interest is that many of the fans of Tolkien before his death were university students...and the Hobbit was actually in regards, overall more popular than the Trilogy.
However, I would say that Tolkien will be considered a classic in years to come, as far as the English language is concerned, for changing the face of what was seen as fantasy. Fantasy existed before Tolkien, but fantasy as per today, with adult Fantasy, was more the range of collectors of such items As Andrew Lang, who appealled to both adult and children. Now Fantasy is seen as more of an adult taste, at least along the lines of Tolkien Fantasy...which in many ways, has created an entirely NEW genre of literature.
In that, obviously he would be considered as much of a classical writer as the likes of Jules Verne, or HG Wells.
But better? That's a matter of opinion I would say.