\[ y''(x)-\cot (x) y'(x)+y(x) \sin ^2(x)=0 \] ✓ Mathematica : cpu = 0.024718 (sec), leaf count = 19
DSolve[Sin[x]^2*y[x] - Cot[x]*Derivative[1][y][x] + Derivative[2][y][x] == 0,y[x],x]
\[\{\{y(x)\to c_1 \cos (\cos (x))-c_2 \sin (\cos (x))\}\}\] ✓ Maple : cpu = 0.094 (sec), leaf count = 15
dsolve(diff(diff(y(x),x),x)-diff(y(x),x)*cot(x)+y(x)*sin(x)^2=0,y(x))
\[y \left (x \right ) = c_{1} \sin \left (\cos \left (x \right )\right )+c_{2} \cos \left (\cos \left (x \right )\right )\]