Which thermodynamic parameter is not a state function?

$H$ and $U$ are state functions but $W$ and $q$ are not state functions. From the equation, $\Delta H=\Delta U+\Delta P V$ At constant pressure, $\Delta H=\Delta U+P \Delta V$ At constant volume, $\Delta H=\Delta U+V \Delta P$ At constant pressure, $\Delta P=0, \Delta H=q_p$ so, it is a state function. At constant volume, $\Delta V=0, \Delta U=q_v$ so, it is a state function. Work done in any adiabatic process is state function. $\Delta U=q-W \quad(\because q=0)$ $\Delta U=-W$ Work done in isothermal process is not a state function. $W=-q \quad(\because \Delta T=0, q \neq 0)$