It's probably Huitzil, just because he's one of the three characters to not return for Darkstalkers 3 (well, he wasn't in the original version of 3).
I also think that compared to Pyron and Donovan (the other two absent from DS3), he's the least important missing character. Pyron has final boss status and Donovan is the designated MC of DS2 and the anime. Meanwhile Huitzil is just the sub-boss for DS1/2 and, from a lore perspective, he's not even unique, as there's a whole army of Huitzils around. The only thing differentiating the playable one is that they're 'good'/malfunctioning
(I actually doubt anyone is familiar enough with Darkstalkers lore to dislike Huitzil for this reason, I just wanted to post some gifs from the anime)
I also think that compared to Pyron and Donovan (the other two absent from DS3), he's the least important missing character. Pyron has final boss status and Donovan is the designated MC of DS2 and the anime. Meanwhile Huitzil is just the sub-boss for DS1/2 and, from a lore perspective, he's not even unique, as there's a whole army of Huitzils around. The only thing differentiating the playable one is that they're 'good'/malfunctioning
(I actually doubt anyone is familiar enough with Darkstalkers lore to dislike Huitzil for this reason, I just wanted to post some gifs from the anime)