Stats are not to prove that spinners are better. Great pacers is always better because they can be effective in all surfaces, but simply showing that spinners are underrated by many fans. Spinners can bowl long spells to keep control. Also, I see tendency to over rate pacers by many fans despite them not being top class just because they have lower average in conditions where spinners don't get much help from surface. That's expected but are they running through sides outside of home enough to be more valuable for their teams?
Case in point, Anderson and Ashwin. Many will point to poor returns of Ashwin in SA and Aus. But in his career, he has contributed more in wins than Anderson, home , away and all conditions taken together. He was also intrumental in series win in Aus by bowling long spells and keeping it very tight. Pacers can't bowl long spells to tie up one end and in case of Anderson, he simply does not have skills to run thorgh sides outside of Eng either.
Anderson despite playing so long has just 3 5-fers in win outside of his home. Ashwin has 5 5-fers in win outside home despite having a much shorter career. Both average 29-30 outside of home. Home and away both, Ashwin has contributed more than Anderson for his team, but very few sing songs of spinners. Same situation with Yasir Shah from Pakistan. He has 6 5-fers in win outside of home compared to Anderson 3 despite playing for 20 years.
I took Anderson as an example because spinners are somewhat condition dependent and Anderson was also condition dependent bowler. All the praise for Anderson and credit for having near 200 tests but he has just 3 5-fers in wins for Eng when not playing in Eng. I mean he got plenty of pace friendly venues and pitches in his career when playing outside of Eng.
Now if you ask me top tier pacers vs top tier spinners. I will take top tier pacers any day. Reason is simple, Top tier spinners have been dominated by gun batsmen more often, but it's harder to dominate top tier Pacers. Case in point, Warner was thrashed in Ind and WI. Murali was thrashed in Ind and Aus. So spinners can be thrased in 2-3 venues despite being great. Top tier pacers don't get thrashed so easily. Just becasue of this reason, top tier pacers over top tier spinners. But after top 8-10 top tier pacers, I will say top tier spinners are more valuable for their teams even if I consider all conditions. Tieing up one end for a long period is very under rated but it helps bowlers on other end.