In my experience, Android tablets may not start out running slowly, but they soon get there. iPads run at the same speed, for better or worse, from the time you turn them on to the time they are set aside for newer equipment. Android tablets go dead in three days of idle time. An iPad can stay alive for couple of weeks.
Keep in mind that I’m an Android fan. It’s my phone platform of choice. But with tablets, spring for an iPad. Apple has won this battle, IMHO.