Although there are probably 4 times as mny mechs that I wouldn't want to see in the game, here are my top 20.

Top 20 dumbest mechs:

1- http://www.sarna.net/wiki/Duan_Gung

2- http://www.sarna.net/wiki/Commando

3- http://www.sarna.net/wiki/Arctic_Fox
Omnimech fail

4- http://www.sarna.net/wiki/Axman
destroy all of these and murder those who has any memory of it

5- http://www.sarna.net/wiki/Buccaneer_(BattleMech)
Avast! I wanna keel haul this piece of ####

6- http://www.sarna.net/wiki/Clint

7- http://www.sarna.net/wiki/Falcon
another scrap heap that's full of fail

8- http://www.sarna.net/wiki/Gurkha
A sword and smoke stacks? Even Conan thinks this mech sucks.

9- http://www.sarna.net/wiki/Hatchetman
See Axman

10- http://www.sarna.net/wiki/Hermes
The look on its face almost pleads to be put out of its misery

11- http://www.sarna.net/wiki/Hoplite
Huh?

12- http://www.sarna.net/wiki/Imp
Danger Will Robinson. Danger!

13- http://www.sarna.net/wiki/No-Dachi
Seppuku anyone?

14- http://www.sarna.net/wiki/Kintaro

15- http://www.sarna.net/wiki/Ostroc
Secret weapon: stop victim in their track with gut busting gales of laughter

16- http://www.sarna.net/wiki/Panther
Remind me never to enlist with the Draconis Combine

17- http://www.sarna.net/wiki/Rokurokubi
See No-Dachi

18- http://www.sarna.net/wiki/Wyvern
I want to beat this thing until it stops twitching

19- http://www.sarna.net/wiki/Stinger_LAM
It HOLDS its gun instead of being attached AND it's absolutely retarded looking

20- http://www.sarna.net/wiki/Ti_Ts%27ang
Another ax carrying misfit

Honorable mention:
Mechs that should also be consigned to the scrap heap

Cossack
Kabuto
Lancelot
Nexus
Piranha
Prometheus
Quick Draw
Red Shift
Spartan
Trebuchet
Valkyrie
Vindicator
Vulcan
Whitworth

What's your list?