Although the scales of the conflics gradually differ, both shows explore, in somewhat realistic matter, the situation in which a Mech should minimize the casualties for the commonfolk in urban settings while fighting, which is kinda uniquie viewpoint for the mech genre in general.
Both shows are sci-fi oriented, and there are alot of simmilarities with the lead heroines, they got simmilar looks and behaviour, they both are affiliated with the police force, and they both adore the machine they operate. Both shows have a lot of comedy in it, although Patlabor is more nuanced, while Dominion is straight up comedy.
Active Raid is like an updated, funkier silly copy of Patlabor in many aspects. You'll probably find your self comparing not only the main plot but also many characters of these series if you watch them both. If you enjoy slice of life shows accompanied by mecha action and a bunch of mismatched eccentric characters you may enjoy Patlabor to the fullest.
What brings these two vintage anime series together more than anything is how the series mixes comedic episodes with darker stories. Episodes can be cool or silly, which can be problematic if silly humour bore you. For most people, Lupin III and Mobile Police Patlabor will not be their first entry into both franchises. As such, the shift in tones will like be a shock when compared with their more popular movies. Luckily, you'll be prepared for that!
Although a decade separates their release, Patlabor and Master Keaton are adapted from manga created using the same mangaka ethics. They are character driven shows that avoids fast faced, action oriented techniques used in mecha or adventure anime/manga. They have no overarching plots, but instead tell simple and concise stories. Both series would have a hard time connecting with a modern (male) audience if they were widely available today. Yet, Patlabor and Master Keaton have their charms that makes them beloved by old-school anime watchers.
These anime both depict characters with relatively mundane lives in extraordinary settings, and provide a counterpoint to other shows within their specific subgenres. Patlabor is to mecha as Planetes is to hard sci-fi. As a contrast to most other shows of these types which involve constant strife and warfare, these shows depict how humanity can live peacefully with advanced technology and noticeably put emphasis on human drama instead of epic battles, although both do eventually take more dramatic twists.