\[ y'(x)=\frac {e^{b x}}{e^{-b x} y(x)+1} \] ✓ Mathematica : cpu = 0.441927 (sec), leaf count = 101
DSolve[Derivative[1][y][x] == E^(b*x)/(1 + y[x]/E^(b*x)),y[x],x]
\[\text {Solve}\left [\frac {1}{2} b \left (\log \left (-b e^{-2 b x} y(x)^2-b e^{-b x} y(x)+1\right )+2 b x\right )=\frac {b \tan ^{-1}\left (\frac {(b+2) \left (-e^{b x}\right )-b y(x)}{b \sqrt {-\frac {b+4}{b}} \left (e^{b x}+y(x)\right )}\right )}{\sqrt {-\frac {b+4}{b}}}+c_1,y(x)\right ]\] ✓ Maple : cpu = 0.377 (sec), leaf count = 98
dsolve(diff(y(x),x) = 1/(y(x)*exp(-b*x)+1)*exp(b*x),y(x))
\[y \left (x \right ) = \RootOf \left (-{\mathrm e}^{\RootOf \left (\left (\tanh ^{2}\left (\frac {\sqrt {b^{2}+4 b}\, \left (-2 b x +2 c_{1} b -\textit {\_Z} \right )}{2 b}\right )\right ) b +4 \left (\tanh ^{2}\left (\frac {\sqrt {b^{2}+4 b}\, \left (-2 b x +2 c_{1} b -\textit {\_Z} \right )}{2 b}\right )\right )-4 \,{\mathrm e}^{\textit {\_Z}}-b -4\right )}-1+b \textit {\_Z} +b \,\textit {\_Z}^{2}\right ) {\mathrm e}^{b x}\]