The Patlak-Keller-Segel system with logistic sensitivity has been widely advocated as a model which avoids over-crowding and generates complex patterns. Here we also consider the general case of a nonlinear diffusion of porous medium type with exponent $m$. The complexity of the observed patterns makes it complicated to understand the processes at work. Here, we analyse the pattern formation ability of such a system, which depends highly on $m$ and three different analyses are needed for $m=1$ (linear diffusion), for $1 2$ but not for $m <2$. We focus specifically on the conditions for long term convergence to the constant solution, uniqueness of the steady state and on the contrary, existence of increasing steady solutions in dimension one. Our method is based on several tools, energy functional, reduction to a single equation, reduction to a first order equation. A major difficulty, in opposition to the case $m=1$, is that solutions can vanish locally when $m>1$.