This is a very subjective question. You could give just about any answer, and it will be correct, or wrong, depending on who you ask. For me, there are many things that make my life worth living. For instance, there's a game series I love. This game series, I can't say it's as good as Mario, or Zelda, or Half-Life, or LucasArts adventure games from the 1990s, or Fallout, and yet, I still love it. Why? Beause it has two things that I live for.
"Cute girls and good music?"
Why yes!
"Wait, that could refer to Key Visual Arts games, or Touhou . . . which one?"
Well, I just finished the first part of a new Touhou fanfic series that I'm writing, but first, allow me to sound like a hipster for the next few paragraphs.
(For best effect, read the following section in the voice of The Cinema Snob. In fact, consider this a segment by . . . the Doujin Snob.)
Ever since the announcement of Ten Desires, fans' love of Youmu have been popping up everywhere. You can't go on a messageboard without seeing her face on someone's avatar. Youtubers have been upvoting remixes of Youmu's themes like Takashi Takeuchi sketching the female cast of Fate/Zero in maid costumes. The Boorus have become flooded with even more artwork of her than usual, in some cases, even outnumbering her master and fan-favorite Yuyuko!
Bunch of fucking bandwagon jumpers. I was whoring myself to Youmu long before Ten Desires even existed in ZUN's head!
(Okay, switch back to my normal voice)
Regardless, here's a remix for you, by IOSYS, and about Youmu.
Say, I could do a whole chapter about Youmu in my new series. I think I will in the future.