\[ \left (x y'(x)-y(x)\right ) y''(x)-\left (y'(x)^2+1\right )^2=0 \] ✗ Mathematica : cpu = 1.41835 (sec), leaf count = 0 , could not solve
DSolve[-(1 + Derivative[1][y][x]^2)^2 + (-y[x] + x*Derivative[1][y][x])*Derivative[2][y][x] == 0, y[x], x]
✓ Maple : cpu = 0.474 (sec), leaf count = 66
\[\left \{y \left (x \right ) = x \RootOf \left (c_{2}+\int _{}^{\textit {\_Z}}\frac {-\textit {\_f} +\RootOf \left (c_{1} \textit {\_Z} \textit {\_f} -c_{1} \textit {\_Z} \tan \left (\frac {1}{\textit {\_Z}}\right )+c_{1} \textit {\_f} \tan \left (\frac {1}{\textit {\_Z}}\right )+\textit {\_Z} \textit {\_f} \tan \left (\frac {1}{\textit {\_Z}}\right )+c_{1}+\textit {\_Z} -\textit {\_f} +\tan \left (\frac {1}{\textit {\_Z}}\right )\right )}{\textit {\_f}^{2}+1}d \textit {\_f} -\ln \left (x \right )\right )\right \}\]