You can kill Benny right after creating your character - if you know how.
You can do it without dedicating your new character to a specific kind of playstyle and you can do it without getting bad reputation from any faction.

Killing Benny sets you up for an easy ride for small gun users (Bennys unique gun 'Maria' is awesome) and unarmed fighters ('Love and Hate' remain useful for a very long time), but you can use this method to set you up for an easy energy weapon game too, by sneak killing all the friendly robots in REPCONN headquarters for the Q-35 matter modulator.

The key items needed to get things rolling:
1 gun (the tutorial varmint rifle will do)
1 stealth boy (found in goodsprings school, needed to sneak past cazadores)
1 steady (aquired from start, needed to shoot the plasma grenade in the hand of the viper leader in Bonnie Springs)
1 unique spiked knuckles 'Love and Hate' (found on above viper leader's corpse)

Also, you should invest a decent number of points in sneak as this will make unarmed stealth kills in friendly territory much easier.

This short ~25 minute trip will also raise your levels from 1 to 5 in the process. No reason to not starting every game like this.

The trip to dominance in a nutshell:
1. grab rifle, stealth boy and steady in goodsprings
2. sneak north to bonnie springs
3. kill viper gangsters and grab 'Love and Hate'
4. travel to new vegas
5. sell your loot to get past the credit check
6. travel to The Tops
7. kill benny

afterwards you might just accept caesar's invitation to visit the legion camp and kill everyone inside. :D one more stealth boy should be enough to murder his personal bodyguard inside his tent without anyone noticing the flying bodyparts.

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