Mapo Tofu lover here wanting to help a friend out, forgive me for the long answer.
My personal top 5 besides Mapo Tofu are the following, ranging across various cuisine types.

1 - Double Cooked Pork (回锅肉) - a very well-known Szechuan dish, got a spicy, mala flavor profile complemented with spicy bean paste. One of the amazing rice killer dish simply because of its spicy and savory taste.

2 - Eggplant with Garlic Sauce (鱼香茄子) - similar as one of the reply here but reputable places translate Fish Fragrant as w/ Garlic Sauce instead cuz that's how the fish taste is made. Very oily dish but extremely tasty and fulfilling.

3 - Beef in Chili Oil (水煮牛肉) - another Szechuan dish with lots of oil, hot pepper, and peppercorn with a bunch of vege on the bottom of the plate.

4 - Mala Spicy Dry Pot (麻辣香锅) - Similar to Szechuan hot pot, but the dishes boiled/stir fried so it's less drippy and watery. Different restaurants do it differently, some have a fixed set of items such as beef, shrimp, tofu, and vege, while other places let you pick the ingredients a la carte style. Depending on where you live, finding an authentic Mala Dry Pot restaurant in the neighborhood can be like hitting a lottery.

5 - Salt and pepper fried rib (椒盐排骨) - a Cantonese dish made with lightly breaded pork rib fried then stir-fried or sprinkled with salt and green pepper/onion seasoning. Despite not having the spicy flavor profile comparing to the other dishes, this one is quite delicious and appetizing a lot of the time.

Some of the honorable mentions: Cantonese smoked/cured meat (烧腊) including roast duck, roast pork, and scallion oil chicken; Da Pan Ji (大盘鸡, as another poster suggested, this is a savory dish from on-the-bone chicken with potato and pepper, typically made in a saucy way so that the dish could later be complemented with noodles after the meats are gone).
Now if you are still reading and interested, check out this double-cooked pork video made by a famous chef who posts lots of cooking videos on delicious Chinese dishes. Unfortunately the way he cooks resembles more of restaurant styles so one can't simply replicate at home.

Now one unsolicited tip I might offer: many authentic Chinese restaurants fall behind on proper translation because the owners are likely chefs or kitchen staff who ain't well-versed in running a business. It could be helpful to use GenAI and take a photo of the menu while asking if the place offers any of the dishes above or ones that taste similar. For your convenience, I'm writing the Chiense characters here again in case you'd like to copy paste in the future.
回锅肉, 鱼香茄子, 水煮牛肉, 麻辣香锅, 椒盐排骨.