Dirk's list matches my own pretty closely especially the top 5. I also like
@Sinis point - I've found in modern EDH that spending a total of 5 mana to play and equip a sword is awkward and clunky outside of dedicated equipment decks unless the Sword specifically synergizes with your plan. So my list is more a tier list.
Tier S: Swords that are borderline format staples if your deck has creatures -
Sword of Feast and Famine. Functionally doubling your mana scales well in this format, and the protections are great.
Tier A: Swords that are excellent and among the best equipment in your format - but that might not make the cut in your '99 if you just aren't looking to run more than 2-3 equipment cards. Staples in equipment.decs and worth a strong look in Voltron decks or decks that can really lean into some of their effects, but not staples.
Sword of Fire and Ice - The
Shock isn't that great, but it's pure gravy alongside all the other value especially "draw a card" and is probably worth it for that effect compared to competition like
Goggles of Night. We still only have a handful of equipment that straight up draw a card on combat damage.
Sword of Forge and Frontier - This is almost like casting
Explore which is obviously great. Extra synergy for decks like
Faldorn, Dread Wolf Herald or
Prosper, Tome-Bound that care about casting cards from exile.
Tier B: Swords that are clearly good, but face a bit more competition. These are hard to horn in to the tuned lists of today unless you have a deck that can really exploit both halves of the sword or are a dedicated equipment tribal deck.
Sword of Hearth and Home - This is just a "bigger"
Sword of the Animist/
Bitterhorn, Nissa's Animus, but those cards superior mana efficiency and the fact you get the land whether you connect or not might edge this out unless you an also exploit the flicker half of the card. You really want both though; you can just cast
Conjurer's Closet for the same total investment without worrying about cracking in in most flicker decks. In practice this has been a bit awkward to include, but equip tribal probably still likes it.
Sword of Light and Shadow - the lifegain is almost an insulting prize, so you have to really have a deck that loves the Raise Dead effect like
Syrix, Carrier of the Flame,
Quintorius, Field Historian, or
Tormod, the Desecrator or a really heavy aristocrat theme. Still okay in equipment tribal since that deck has a lot of tension in running enough equip and enough creatures, and this helps you rebuy creatures.
Sword of Sinew and Steel - this is an incredible amount of value and card advantage when it works, but you're often going to be nailing mana rocks + nothing and generating outsized hate for a mid card. More or less only worthwhile in equip tribal decks.
Tier C: Swords that are falling off a bit in the format, and need a very specific decklist. These start falling off in equip tribal builds because even those decks can only afford 10-15 equipment spells and after the top 5-6 swords above likely want to start looking at stronger effects that synergize with their plan and cards with Living Weapon and For Mirrodin!.
Sword of Truth and Justice - Proliferate on damage is awesome, but you'll really need to invest in counters cards since otherwise just proliferating a single +1/+1 counter is awful. Gx counter decks have more efficient and powerful ways to proliferate or stack counters, so this probably shines in a deck that isn't green, has a significant creature count, and wants a ton of proliferate and even then can feel a bit win-more. That limits this to just a handful of fringe commanders. I'd also note these protections are amongst the worst in this format, since White and Blue are the colors best at removing threats without targeting, damage, or blocking.
Sword of War and Peace - I'd note this doesn't help Voltron decks, since damage from the Sword isn't commander damage. I almost wanted to put this in D tier since I think it's really underwhelming in EDH, but this card is still legitimately scary in a deck with a lot of double-strikers allowing even a small 2/2 double-striker to suddenly end games in a few swings, and can be a strong win-con for a hatebeary aggro deck. Also tends to be better early and mid to late.
Tier D: These swords are only worth running in EDH to say "I ran all 10 swords", as even in decks that synergize it's not what you want to do.
Sword of Once and Future - still salty this isn't "Truth and Lies". Surveil 2 is getting a bit underrated in this thread, but it's also not meaningfully better than what we get out of
Mask of Memory and
Zephyr Boots which I'm really high on. The really awkward part of this is that the decks where a free flashback would be good like
Feather, the Redeemed and
Talrand, Sky Summoner are the decks that are least likely to want to spend the time to set this up. This is also clearly terrible in equip.dec, as that deck has to load up on so many artifacts and creatures that it only has room for like 10-15 spells that aren't that.
Sword of Body and Mind - still the worst imo. A 2/2 body is really mediocre, and
Sigiled Sword of Valeron is competition. I will note there are few equipment that make tokens on hit - it's basically those two plus
Infested Fleshcutter - but that's not an effect most tokens decks want. And milling opponents might be actively harmful to your survival.