An early dagger of pain or elec can certainly get someone to zot, especially if they're more magic oriented. And backstabs from sabres does high damage.
There's a big difference between "it can get you to Zot" and "it can get you Zot easily", and a huge difference between "it can get you to Zot" and "it's the strongest weapon class in the game". I don't play my games with a scimitar of freezing and IMB exclusively even though I am pretty sure I could get to Zot with them, because there are better options available.
Of course the answer given does vary according to the stage of the game we are looking at and the race you picked. Yes, a short blade of electrocution is basically the best weapon you can get on D:1 barring Xom gifts and yes, your SpEn is better off with a dagger of pain than a demon trident of speed - but it's very unclear what exactly is meant by the poll since it doesn't specify location/XL and so I do take it as "the best weapon you could wish for, disregarding apts and current skills" and that isn't a dagger of pain or electrocution, but (in my opinion) a vampiric bardiche. I have several reasons for this:
-reaching is extremely powerful in that it will allow you to avoid taking damage or avoid taking a lot of damage from all slow melee/melee-focussed monsters, and ridiculously powerful with Swiftness/boots of running, optionally adding Haste, because the monster you aren't taking damage from don't even have to be slow any more. This is one of the major reasons why I believe polearms are more versatile/generally powerful than axes nowdays. I also think that they are a class that leans more towards two-hander strength now, if less obviously than Axes, mainly because tridents are "sort of OK", not good, and demon tridents are very rare.
-a character using a reaching weapon will always get one hit more in before he gets hit than a character who isn't. In my opinion, this is enough to compensate for the lack of 2 base damage as opposed to an executioner's axe, even if your opponent isn't slow or you aren't especially fast - you'll usually be taking less damage because the difference in base damage is not very significant, but one extra hit from a really high-damage weapon is significant!
-I think that vampiric brands are superior to speed brands - if your character isn't doing more than two times the damage to a monster than that monster would do to you (exceptions allowed of course), he isn't that strong usually. As such you will often be at or close to high HP and go on meleeing monsters for a lot longer than you would than you could with a speed brand, especially in corridors where you usually should be, and if I have the choice between "killing monsters at double speed" and "killing monsters finishing the fight at full HP" I choose the latter, from the perspective of safety, "strength", realtime and turncount.
-you're wielding a 18 damage vampiric brand weapon which sort of speaks for itself
I think this definitely beats non-form unarmed - and forms, well, we are talking about weapons here and not about spells, right? And I'm really not sure if I would want to give up my reaching and vampiric benefits just for significantly more raw damage, even in the case of Blade Hands.
Stabbing - well, I think it's a lot less versatile and while, for instance, SpEn is a very strong build, you will find that this is not just because of the stabbing, but also because of extremely high survivability not due to weapons but to the Sp part, and great ninja powers not connected to weapons but to translocations, the Sp part, Haste, other buffs and Invisibility.