A weighty decision: Medium vs Heavy Armor
Choosing between medium and heavy armor can often be a challenge. It’s obvious when to wear light armor; if you’re a dexterity focused character, or if it’s the only armor you have proficiency in, pick it. But medium and heavy, due to being closer in design (both need around a 14 in a certain stat to use effectively), can often be harder to choose between.
AC
By raw AC alone, heavy armor is slightly better, leading by 1 point. However, out of the armor options available at character creation, there’s no difference between AC from the heavy options versus the medium options. To squeeze out that extra point of AC, characters are forced to spend 1500gp on full plate, one of the most expensive mundane items in the game.
Stats
Heavy armor is oddly designed. Unlike medium armor, the AC it grants doesn’t depend on your stats to reach its full potential. However, it drastically reduces your speed unless you meet the strength requirement (15 for full plate) needed to use it without penalties.
Fundamentally, heavy armor is dependent on Strength, a much less useful stat than Dexterity. Dexterity is one of the Big Three most common saving throws, boosts your initiative (which is much, much more impactful than it seems), and boosts some very important skills, especially Stealth. Furthermore, weapons that use Dexterity generally deal more damage, and can operate at range. In contrast, Strength is practically useless for almost all characters. Consequently, almost all characters want at least some dexterity, making medium armor much more affordable.
Negating the strength requirement?
However, there’s a few ways to circumvent the strength requirement.
- Armorer Artificers can ignore it entirely
- Most viable melee characters will be strength-based, and consequently already have a high enough strength
- Mounts can negate the movement speed penalty, but aren’t very durable, and can’t fit into small spaces such as dungeons or caves. The Phantom Steed spell is an exception, since it’s fast enough not to get hit.
- Some magic items, such as Mithral armor, remove the requirement
Some characters also have no choice but to wear heavy armor, because they can’t afford the Dexterity. Paladins need high Charisma, Constitution, and Strength, particularly to meet multiclassing requirements, so are often forced into wearing heavy armor.
Conclusion (and how to choose simply)
Put simply, medium armor is the best bet for the vast majority of characters, given that most characters can access it with a single level in another class. As outlined above, there are a few exceptions, but in one of the strangest design choices in 5e, medium armor is almost always better.