What is your interests? Sir Terry was a consummate satirist, able to reach the heart without being too serious. Here's what I'd recommend off the top of my head:

Pure entertainment: Moving Pictures - an alchemist invents Film, and suddenly everyone is moving to Holy Wood. But as Moving Pictures blur the line between fantasy and reality, something Else wants to see reality as well

It Makes You Think: Small Gods - What is faith? What happens when people replace belief in their god with the institution that surrounds the god? What if the god in question is a bastard? What is worse, the god, or the holy wars that will be made by the next "prophet"? Religion and philosophy clash with the sound of lightening hitting a copper roof

You'll think, but with wordplay: The Truth - Dwarves have learned how to turn lead into gold. The hard way. The printing press has come to Anhk Morpork, and with it, the Press. A commentary on truth, journalism, and politics, with a healthy dose of classism and privilege

For the Feels: Feet of Clay - (this one drops you in the middle of the Watch series, but you won't be in the weeds for long. If you don't want mild spoilers from earlier in the series, save this for later) A priest and a baker are murdered, and the Tyrant of the city has been poisoned. It's up to Sam Vimes to find out what's at the bottom of this mystery. And he could probably do so if it weren't for all of the damned clues. And what do the Golems, those silent machines who toil in the worst places, have to do with any of this? When the servant class isn't considered living, who cares what happens to them?

More Feels: Reaper Man - Death has been fired. But he has been given a retirement gift: The Time of his Life. There's not much of it, because when the next Death is chosen the Reaper Man's time will have run out. A reflection on mortality, time, and the obligation of the Reaper to respect the Harvest. And who will care for the harvest, if not for the Reaper Man?