I realize that Raichu has plenty of fans, but I would've been so happy to see Ash have a Raichu, even if it was in addition to Pikachu. I understand that Pikachu has sold a lot of Pokemon games and merchandise just by itself. But still, Raichu is a far superior Pokemon. If Ash's Pikachu had become a Raichu, Ash would've probably become the most unstoppable force on the planet. He would've broken Pokemon.
Raichu has always been one of my favorite team members while playing the games. He was usually the Pokemon I used more than any other when I played the original Red and Blue. It bugged me in Pokemon Yellow when I couldn't get him to be a Raichu!
Sadly, as time went on, Raichu was on my team less and less because of availability. Over time, I ended up having another electric-type favorite. Still, Raichu will always have a special place in my heart. The amount of pure raw energy that guy can put out is absolutely ridiculous. If I could have any Pokemon in real life, Raichu would be a top candidate.
Photo credit: Bulbapedia