$\mathrm{N}\left(\mathrm{sp}^3\right.$, localized lone pair $)>\mathrm{N}\left(\mathrm{sp}^2\right.$, localized lone
pair $)>\mathrm{N}\left(\mathrm{sp}^2\right.$, delocalized lone pair, aromatic)
$\therefore$ Piperidine $>$ Pyridine $>$ Pyrrole