I haven't seen this comparison yet. This to me is very compelling. Looking at their top 10 OPS and here's what we get:

Hornsby: 222 209 207 201 191 187 185 178 176 169
Musial: 200 183 183 179 177 177 174 172 169 167

Hornsby's peak is better, but Musial crushes Hornsby in longevity. Musial had 3200+ more plate appearances than Hornsby, which is about 5 more full seasons worth. Hornsby OPS+ of 175 beats Musial's 159, but Musial has much better cumulative numbers. Hornsby does get robbed by the deadball era, but Musial played in a tougher era altogether. I'd say Musial squeaks out a victory here for overall career value.