Here are the top 100 arranged by kills per root game.

15.69 wertrew
14.03 trabc
13.13 ersinka33
12.41 Jack Barrows
10.15 gogi
9.96 michele
9.73 Jonjo1
9.29 KingRussy
8.86 Bachus
8.85 Rafkrik
8.76 LearnToLive
8.63 kamikaze Mike
8.27 Michalak1
8.15 kskmemory
8.14 Beach_Bum_13
8.01 Lee34
7.91 Kludge26
7.91 Im Defeated
7.64 Hong Kong
7.55 FreeFalling321
7.44 {A}Monkey SLayer
7.18 panzer
7.17 savif
7.15 hcdug
7.03 Qaziyev
6.89 stakaboo
6.78 potato27
6.65 toms
6.58 prowler-exe
6.57 sexybabe
6.49 billyswong
6.49 habit1
6.48 Gauntlet15
6.47 rofarah
6.39 Clempson
6.37 integral
6.21 Fedya
6.20 Shevar
6.18 vecker
6.15 dahl
5.95 Hobyandy
5.92 Oliversdad
5.91 Rebel9
5.88 orange33
5.84 arkenkor
5.76 Troy11
5.73 thegreenheaven
5.72 Im Iron Man
5.60 Romanoff
5.53 Gurgi
5.24 Slinus
5.23 NikkeKnatterton
5.18 ivv
5.09 Jouster III
4.87 rocka09
4.73 uolter
4.69 Smoke Two Joints
4.64 the_king333
4.63 Kurwa_pendecho
4.58 @DIEGOi14
4.53 Maser
4.37 22 April
4.30 Black Flag
4.23 _BOT_18_
4.16 BigDaddyKane
4.13 PND
4.10 Gnací
4.07 Created
3.99 dicemurder
3.86 Shantaram
3.84 lipos
3.56 spman
3.46 franklyghost
3.40 apignarb
3.34 ireneo
3.33 greeen
3.23 ehervey
3.21 nothin
3.17 Aken
3.16 Soromon
3.16 Larry The Bull
3.12 kdiceplaya!
3.12 MWixxx
3.05 shadolin
2.95 TEOQ
2.93 Ninjamonkey
2.65 geor2205
2.59 RailRyder
2.54 Nerd Alert
2.49 koild
2.22 unlucky4bunny
1.78 EddyB
1.64 VagPounder69
1.50 orestis85
1.18 spman2
0.96 spman3
0.89 Arnas Bro
0.82 jurgen
0.00 GleepGlop
0.00 moulue