Wow! This new thread has been a surprice and I'm happy that we are talking about that, but please don't be too "aggressive" in the selection of cards that you want to remove, because I've seen a general underestimation of cards that instead may have their good use, especially in other formats than Vintage. Power is not the only goal, but also the fun that a card may provide.
What follows is my personal opinion in detail:
Cloned cards - I also agree about removing the ones (as
Moor Fiend or
Ravages of War) that do not offer any benefit in a number greater than 4, while I wouldn't remove some useful ones as the "Pump Knights" or
Fyndhorn Elves (clones of
Llanowar Elves) because there are some decks that can use 8 of them succesfully.
Vanilla creatures - Not all vanilla cards are ugly:
Woolly Thoctar is a vanilla card and is great

But also older ones as Fire/Earth/
Water Elemental or
Grizzly Bears are vanilla cards and are more than decent. So please remove ONLY the ones from the Legends and Dark that have a bad ratio among power & casting cost. Please, don't remove
Jasmine Boreal and
Sir Shandlar of Eberyn.
Unlimited Set - Even if I would be very happy to see the Laces and Unlimited lucky charms disabled (they are not bad but the new ones are much better), remember that changing cards from Unlimited set will affect Shandlar too and thus they can't be removed: in fact, as far as I remember,
Shandlar and the Duel share the same art and CSV (cards.dat), which actively influences cards behavior. Also, Unlimited set has a valued as 99% completed set in sealed game. At this purpose, Wards can have a value for weird combos and as Sideboard Cards, while Banding may be strong in such game modes with a low ratio of direct anti-creature spells.
Legends & Dark - I know that those sets did include a lot of junk, but please don't be too radical in removing them all. Eg, I don't see any reason to remove the mana batteries, since they can be useful in Sealed Deck games. There is much worst to start from.
Astral set - For reasons that I've explained elsewere, I would remove all of them except
Aswan Jaguar and Fairy Dragon. But changing them would affect Shandlar too.
Ante Cards - Ante is part of the game, there are ante modalities and so those cards can be used in sealed deck game and may be very powerful (especially
Contract from Below). IMHO, they should NOT be removed.
Bouncelands - I dislike them too, because they are very slow and because the AI makes a terrible use of them.
If you really want a solid list of cards to remove, let's start from here: they are already
34 free slots, so there is no reason to start "killing" other cards.
8th EditionCoastal Hornclaw (it is the only card from that set which is really ugly!!)
Unlimited Laces (just disabled)
Manalink 2.0 the five "voice of ..." Angels. With
Voice of All, they are all made obsolete. Even if they have other minor advantageas, as a less-confusing use for AI, lower rarity in sealed deck and a slighty cheaper casting cost, those advantage do not compensate the space that they take.
Legends.557
Aisling Leprechaun - can't find any application, there are better pixies
.577
Barktooth Warbeard - vanilla and/or ugly creature
.669
Hell Swarm - surpassed by
Marsh Gas.667
Headless Horseman - vanilla and/or ugly creature
.676
Hunding Gjornersen - vanilla and/or ugly creature
.689
Jedit Ojanen - vanilla and/or ugly creature
.695
Kasimir the Lone Wolf - vanilla and/or ugly creature
.708
Lady Orca - vanilla and/or ugly creature
.727
Mold Demon - vanilla and/or ugly creature
.748
Princess Lucrezia - vanilla and/or ugly creature
.744
Planar Gate - too mana-expensive for being used
.757
Raging Bull - vanilla and/or ugly creature
.759
Ramirez DePietro - vanilla and/or ugly creature
.776
Riven Turnbull - vanilla and/or ugly creature
.790
Sivitri Scarzam - vanilla and/or ugly creature
.388
Word of Binding - just ugly
.721
Mana Matrix - too mana-expensive for being used
.620
Elder Land Wurm - vanilla and/or ugly creature, personally would like to see it "upgraded" to
Alabaster Dragon or another nice white dragon.
.621
Elder Spawn - vanilla and/or ugly creature
Dark.308
Coal Golem - useless mana source
.314
Erosion - out of flavor for blue, useless
.937
Goblin Rock Sled - ugly even as sidebard card vs. red
.335
Hidden Path - self-suicide card
.343
Mana Clash - useless and ugly
.345
Martyr's Cry - ugly and extremely limited
.948
Squire - made obsolete by tons of better cards, useless even in sealed deck
.950
Tivadar's Crusade - too specific and useless, since we don't have a sideboard.
Also, even if it is not so bad by itslef, I would prefer to see
Angry Mob upgraded to
Crusading Knight.
Even more, I wouldn't remove
Righteous Avengers because it may be a nice sideboard card in Sealed Deck and would never remove the ugly (I know)
Akron Legionnaire for affective values: when I was a kid, I did a deck with
Urza's Land,
Angelic Voices and only Artifact creatures to use the Legionaire and I love to have it here on the PC

Pleaseeeeeeeee
