\[ x y'(x)-y(x) f\left (x^a y(x)^b\right )=0 \] ✓ Mathematica : cpu = 0.276621 (sec), leaf count = 186
DSolve[-(f[x^a*y[x]^b]*y[x]) + x*Derivative[1][y][x] == 0,y[x],x]
\[\text {Solve}\left [\int _1^{y(x)}\left (-\frac {b}{\left (a+b f\left (x^a K[2]^b\right )\right ) K[2]}-\int _1^x\left (\frac {b^2 K[1]^{a-1} K[2]^{b-1} f'\left (K[1]^a K[2]^b\right )}{a+b f\left (K[1]^a K[2]^b\right )}-\frac {b^3 f\left (K[1]^a K[2]^b\right ) K[1]^{a-1} K[2]^{b-1} f'\left (K[1]^a K[2]^b\right )}{\left (a+b f\left (K[1]^a K[2]^b\right )\right )^2}\right )dK[1]\right )dK[2]+\int _1^x\frac {b f\left (K[1]^a y(x)^b\right )}{\left (a+b f\left (K[1]^a y(x)^b\right )\right ) K[1]}dK[1]=c_1,y(x)\right ]\] ✓ Maple : cpu = 0.12 (sec), leaf count = 39
dsolve(x*diff(y(x),x)-y(x)*f(x^a*y(x)^b) = 0,y(x))
\[\int _{\textit {\_b}}^{y \left (x \right )}\frac {1}{\left (f \left (x^{a} \textit {\_a}^{b}\right ) b +a \right ) \textit {\_a}}d \textit {\_a} -\frac {\ln \left (x \right )}{b}-c_{1} = 0\]