I have to say I’ve always liked the Royal Knights as a group, but if I have to pick favorites then I really love Gallantmon/Dukemon because of Digimon Tamers and Dynasmon and Examon have grown on me in recent years.
I always liked UlforceVeedramon best cuz his design alone won me over, topping Magnamon. They've always been my favorites just for the spectacle whenever they make an appearance (Magnamon with extreme jihad in 02 or ulforceVeedramon in V-Tamer). But I also really like leopardmon cuz its cool that he has a leopard mode, having different forms for different situations makes him stand out, ad knowing that he's the team's tactician makes him more vital than many of the others. I've also grown to like Crusadermon, her elegant demeanor mixed in with her "ends justify the means" makes her very memorable, and her actually being the leader of a whole species (Knightmon) is really cool.
Craniumon, lord knightmon, and dynasmon for me! And of course dukemon, because I'm very biased toward Tamers. 🤣I really like craniumon's design the best, he has a sort of skull face and it stands out from the other knights in a neat way.