Which would be best on different types of wickets?
Spicy, pace-dominant: pacers
Flat, pace-dominant: close (good luck to the health of pacers bowling 30 overs on day one)
Spicy, neutral: close, but pacers
Flat, neutral: spinners
Spicy, spin-dominant: spinners
Flat, spin-dominant: spinners
Pace-dominant wickets in the general sense of the term are slightly more common in test cricket than spin-dominant wickets. But it doesn't resolve this discrepancy.
More pacers are picked than spinners, generally, because spinners can bowl more than pacers. That reasoning is nullified if instead of 4 or 5 bowlers being picked, you've only got 3 spots.