"The Enemy" MIGHT be good but one could argue you have to know and understand the tension between the Romulans and the Federation in order to fully appreciate moments of it, in particular Worf's personal feelings towards Romulans.
Not really though, because Worf's dialog puts it all out there in plain English as to why he will always hate them. It's not even really necessary to have any back story on Romulan/Fed relations. It's simple. Like the title says. They're enemies, & that's all there is to it, & they highlight two sides of that coin
Don't get me wrong. The Defector is a better episode than The Enemy, but you really do need to have some sense of what Romulans are all about, to digest that one. I picked The Enemy specifically because it has many elements of what TNG is, but doesn't require any foreknowledge. A person who'd never even heard of Star Trek could watch it & figure out everything that's going on
It would keep them interested. It would introduce them to everything about TNG, their methods, their codes & policies, their technology, & tidbits about the alien races. There's a neutral zone. The enemy crossed it. There's lives at stake. It all has the potential to go horribly wrong, & in the end things work out, because it's Star Trek. Not to mention that Geordi is like a genius in that episode
Uses his visor to spot ore in the dirt to melt with his phaser into climbing spikes. Programs a tricorder from memory, to communicate with his visor, without ever even touching it,
He's like a bloody blind Batman in that episode!