Sherlock Holmes loves John Watson for many reasons. Even with his giant intellect he isn't able to list all of them. Mostly because every time he thinks he knows all of them, John Watson shows him something new, something he loves just as much as other things. His doctor is a never-ending puzzle with so many small elements... Other times John reminds him of reasons he had almost forgot. Like the fact that when it's winter John is always doing a cocoa in the evening.
Sherlock loves his smile (so bright and kind). The way he giggles (because the way John Watson giggles is the most extraordinary chuckle he ever heard). His face when he is asleep (peaceful and relaxed). He adores the fact that John is always preparing him a cuppa when he is working (it doesn't help because he is focusing on his doctor then, but he likes it anyway), and leaves him breakfast if John has left for work before he gets up (but he never leaves the flat without waking him up, saying 'hello', kissing and wishing him a good day), or buying the milk (which Sherlock never remembers to do).
Sherlock admires him when John is protecting Sherlock (from Mycroft for example); taking his side (in front of Lestrade and his men); fighting for him (his brave, so very brave soldier). He wouldn't say it out loud, but he worships John at those moments (he doesn't have to say it, John knows it just the same).
Sherlock Holmes admires John Watson (his doctor, soldier, blogger, lover, partner, very best - and only - friend) and would - and done or tried - everything for him. He has become more human (because his friend treats him like a human being). He is trying his best to be a boyfriend and go on a few dates (since his lover likes to show him off everywhere like he is some kind of trophy wife). He tries to take better care of himself (for his doctor, who is asking for it not-so-kindly). He fails trying to keep his mouth shut (but it isn't necessary anyway, since his blogger doesn't write down everything). He is trying to be more careful (for his soldier, who isn't always by his side to protect him). He even tried - and failed - to take care of housework (but his partner was happy that he tried).
In the whole world there is only one reason for Sherlock to hate his doctor. It is because John H. Watson isn't immortal, unstoppable, indestructible. And for that one, so simple, so plain a reason, Sherlock Holmes hates his partner at some points in his life (when John is lying in with fever, or when Sherlock is sitting in the hospital, hoping his brave soldier is going to be all right, or when he saw the first gray hair on John's head).
But then John H. Watson would smile, take his hand, kiss him, make him laugh, and everything would be okay again. Because he couldn't be mad at this man forever, or even for few days.