I really like most all of the Sailor Senshi, but my favorite characters in that show were pretty much all villains. Season 1 villains didn't capture me as much, but the aliens and Ayakashi Sisters from Season 2 stole my heart...followed by the Witches 5 and Mistress 9 and the Snow Queen from the S movie...then came the Amazoness Quartet, and finally, the Sailor Animates and Sailor Galaxia. They're all so awesome!
Your fanart is really great too! You got their personalities down pat, and I love the detail you've included!