Here are the top 100 players who have played at least on regular game ranked by kills per the square root of the number of games.

21.12 AmericanHist0ryX
17.39 DO3
12.36 Cristiano917
10.81 Jack Barrows
10.76 michl
10.20 Intuition
10.10 BAMMBI
10.07 LololeRastA
10.00 axlehammer
9.56 arkenkor
9.11 BerlinerSportClu
9.10 Ninjamonkey
8.86 gtoo
8.84 avesano
8.74 stakaboo
8.59 orgi
8.54 kolaps
8.41 ghj luigi
8.32 Emz811
8.21 Harlequin UZ
8.16 Nazgra
8.15 Hero Of Time
8.07 Beach_Bum_13
7.97 dragonfly500
7.94 dunnoy
7.70 swatti
7.53 twinky
7.53 DieNoobs
7.37 Lauch mit Schlau
7.23 WillDeed
7.15 ProxyCheater
7.11 TimeR_rW
7.09 22 Apr
7.03 integral
6.93 peacefrog
6.93 SlapDice
6.90 masticore
6.90 hcdug
6.88 Pedeeer
6.70 lee pardon
6.61 cemt2307
6.59 MNML
6.55 SOCRATES SLB
6.54 Orthros
6.31 Glen Carr
6.25 toms
6.18 slim p
6.13 Kludge26
5.85 Oliversdad
5.76 Ariergarda
5.38 GodAlmighty
5.17 OleMcDonald
5.15 Udosuh
5.13 th_rush
5.12 Afro
5.12 Vermont
4.97 Adam Candee
4.85 REMCO
4.83 Captain Ramius
4.71 ireneo
4.65 pipacs
4.64 aida-ludens
4.35 MadMadMad
4.29 rushwing
4.17 ProKennex
4.10 Scorpionsfan
4.09 Nerd Alert
4.02 spman
3.84 SL_Assassin
3.81 Ingvar Gylfason
3.62 Hong Kong
3.60 Chris is King1
3.40 mcdouggal
3.33 Matthias
3.25 rofarah
3.13 piers plowman
3.09 spman9
3.07 blacksmith42
3.05 ivv
2.76 Tropico
2.68 tetyos
2.67 spman2
2.56 Bandi
2.54 xxerox
2.51 chronogame
2.51 Alex Closson
2.50 SprintTx
2.46 wool
2.22 moulue
2.09 orestis85
1.90 GleepGlop
1.79 PureOdyssey
1.79 B4M069
1.75 spman4
1.41 S3Z0
0.80 Grux
0.65 PRESIDENT N° 1