I compiled a list of all the LCS weeks where a team emerged the undisputed #1 in the LCS. C9 holds the all-time record, and is also the only team to have sat alone at the top for an entire split (S3 Summer). Alliance do best in EU, where more teams (8 to 6) have held #1 uncontested than in NA. Curse do surprisingly well considering they were only dominant during one split - they have the same number of undisputed weeks as Fnatic, though since Fnatic are still competing that will likely change.
Cloud9 (S3 Summer, W1-9, S4 Spring, W11, S4 Summer, W11) (12)
TSM (S3 Spring, W11, S4 Spring, W2-9, S5 Spring, W4-5) (11)
Curse (S3 Spring, W1-2, S3 Spring, W5-9) (8)
Dignitas (S3 Spring, W4, S4 Summer, W2) (2)
LMQ (S4 Summer, W1, 9-10) (3)
Team Liquid (S5 Spring, W1) (1)
Alliance (S4 Summer, W2-11) (10)
Fnatic (S3 Spring, W3, 6-8, 10, S4 Spring, W1-3) (8)
SK Gaming (S4 Spring, W11, S5 Spring, W3-5) (4)
Team Alternate (S3 Summer, W1-4) (4)
Lemondogs (S3 Summer, W8-10) (3)
Gambit (S3 Spring, W4-5) (2)
Roccat (S4 Spring, W5-6) (2)
Evil Genuises (S3 Spring, W2) (1)