Why does Team Rocket always try to catch Pikachu? Very surprised this question has not been asked yet.

In almost every single episode, at least from the first season all the way through to the Unova region, Team Rocket is trying to catch Pikachu to give him to Giovanni. Why do they do this? They often cite reasoning that this Pikachu is special somehow, but is that actually true? Nobody else really talks about how awesome Pikachu is, and he certainly doesn't seem to win very often.

I'm looking for any kind of answer, in-universe, out-of-universe, thematic, humourous, etc.

I have a theory I will post below but wonder if this community could come up with a better answer.
There are multiple reasons (and theories. People won't give up with Pokémon theories &amp; creepy pasta) of why Team Rocket would like to get Ash's Pikachu.

1) In ep65 "The Battle Of The Badge" in Season One, it revealed that the boss asked them to, by team rocket saying to the Jovani "It's even rarer than the Pikachu you want so much". the question remaining is what makes Ash's Pikachu so rare and special? 


  In the Season one episode "Ash Catches a Pokémon," when Team Rocket was trying to steal Pikachu, Meowth accidentally says that Ash's Pikachu's power exceeds the power level he would possess as a Raichu (the evolved version of Pikachu). 


As said in the wiki, as an example. (I'll try to update the post with a video link). 

Which can be interpreted as


  Ash's Pikachu has got more power than a regular Raichu


As you can see in the different seasons of Pokémon, Ash's Pikachu is dunking asses. If you compare it to a regular Pikachu from one of the games, the difference in stats is ridiculous. I mean like... really?

What's more, Pikachu is one of the few Pokémon Ash didn't abandon (I mean.. C'mon, he left Charizard, who in the world would be insane enough to do this? What do you mean, Pokémon have feelings too?), so Ash spent many years training him. 

So we can assume that, even if Ash was one of the most incompetent trainers,  Pikachu should be around level 100, giving the Team Rocket another good reason to try to catch him.

2) Another way to see it (not proven at all, just my personal opinion) is that, more than being stupid, Team Rocket is incredibly stubborn, as proven by the hundreds of tries of catching Pikachu. They spent years trying to catch Pikachu, what would be the sense of all this time of their lives if they stopped now? They prefer to keep spending their time trying to catch this Pikachu rather than admitting they lost years of their lives for nothing.

TL;DR : Pikachu OP &amp; Team Rocket stupid