I think if any element should have the best shield of all, it should be
... though in elements it seems to be more offensive than defensive... which seems strange in my opinion. But anyway
and
could be second in my opinion.
I don't know how strong/weak
is, because I never played mono-light, but as far as I see hope works really well in duo and trio decks, also a good alternative to bone wall in rainbows, but it seems too hard to counter...
Most damage reducing shields can be countered easily with high attack creatures.
Gravity shield can be countered with small creatures.
Other shields approximately half damage (procrastination, ice shield, dusk mantle).
Fire shield... depends on deck using it, but still possible to withstand with most decks.
Most of the above can be countered with permanent control, unless protected
Bone wall, on the other hand is good only if you already have control over the field, otherwise it is easily destroyed by creatures, so it is more of a 'when you already have control, make it stay so', rather than helping to establish control.
Also all shields can be countered with momentum, but in this case I would say elements with healing have advantage, because normally the damage that goes through is small enough to heal with bonds/SoG/miracle/vampire/antimatter/etc
But hope seems to be pretty immune to most forms of counter. Can not be destroyed, good against small creatures and good against big creatures, good in early game and good in late game... against momentum miracles might prove a problem.
Ok, creature control solves the problem of late game - killing all the light emitting creatures makes hope an average shield counterable with high attack creatures... but I guess most mono light decks will use luciferined light drags, so will be hard to remove from play, especially by other mono decks. When on the other hand we pit a duo/trio deck against a duo/trio hope deck, the duo/trio deck might have better creature control for example, but duo/trio hope deck will probably have ways to protect luciferined creatures... so I guess any way hope is the hardest shield to counter. And making the best shield also the hardest to counter is in my opinion OP.
So it needs nerfing, either making it less powerful, or (preferably) easier to counter. For example add some conditions when it is destroyed... but I would suggest to link these conditions to the amount of
the player has (something similar do dissipation shield), because it is strongly linked to
production, so it would make sense.
Creature control. And I know what you're going to say, "but what if they're made untargetable?" Simple. Making them untargetable, either with Anubis or Aether Nymph or Quint will require the use of one or two more elements, which balances it out just fine. If someone is willing to use those extra elements, and actually manages to get the shield up and the creatures protected, then by all means, they SHOULD win the match.
Light Dragon + Luciferine/Light Nymph + Guardian Angel/Archangel requires only light, and is still HARD to counter with creature control. All these have a lot of hp and angels can deal with infection for a long time, so you either need a number of damaging spells or an already grown devouring creature or lobo to counter it, but still hard to counter in my opinion.