Engineer is my favourite job.
If you know how you can get anywhere in the station as Engineer, and do anything you want. Usually if you're smart enough you can get away with it easily too.
I enjoy disabling any AI camera I pass, then disabling AI control on some key doors and APCs. Then I sometimes remove the power cells from several important APCs. Including the solar panels APC power cell, rendering the solar panels completely useless no matter what. i also occasionally disable the medical bay with one surgical strike as engineer. I also like to break into EVA and steal the space suit before someone else does. I usually then hide it in one specific place on the station, it makes a suburb hiding area.
I once tried my hand at bomb making, but never liked it that much. I prefer dismantling the station slowly and dramatically. Not just by blowing up medical. I also give the stations good guys a chance to repair the damage.
Although... Probably some of the most fun I've had as engineer was breaking into Atmos Tech and venting all oxygen, while at the same time pumping in N20. Only those with internals knew wtf was going on. But the moment they had to switch their oxygen tanks they were knocked out.