Builds are grouped by primary class, and within each class by New Player / Premium / Outdated Builds.
New Player Builds can be rolled up and played by a brand new player without spending a penny on the game. For premium classes, new player builds are defined as a build that doesn't require any premium features other than the class.
Premium Builds include pay features (premium races/classes, iconics, tomes, harper agent, 32pt builds) or past lives. A brand new player can start with a premium build if they already have the listed premium features unlocked. For example, if the only premium features listed are Gnome and Warlock, a VIP can roll it up immediately.
Outdated Builds include both New Player and Premium builds. There are two reasons a build could be listed as outdated. First, if the author has officially abandoned it due to game changes making something else clearly superior. (eg: Centered Kensei is strong, but the paladin pass made paladins clearly stronger.) Second, if it hasn't been updated since its class trees have been updated. (eg: The Dwarven Defender is a strong S&B tank build, but hasn't been updated since the Vanguard tree was added.) If a build concept has been completely broken by game changes, it won't be included in these lists.
In other words, there are legitimate reasons to consider rolling up any of the Outdated Builds listed in this thread.
Artificer
Barbarian
Bard
Cleric
Druid
Favored Soul
Fighter
Monk
Paladin
Ranger
Rogue
Sorcerer
Warlock
Wizard
Specialty Builds (Challenge Farmers, Event Farmers, Dual-box Openers)
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If you have a build concept in mind but are unsure how to put the pieces together, you can ask for volunteers to craft a custom build for you:
Kent's custom Character Builds by Kentpb
Kentpb has crafted many, many customized builds by request. He also keeps a list of all his builds in the first post.
Request a Build - Get a Build
Possibly the longest-active thread on the forums, approaching 9 years and with over a million views. There's a table of contents in the first post, but it stopped being updated in 2013. The thread itself is still active, so feel free to ask away.
A previous thread with a similar theme: New U19 Builds for Characters by Battlehawke
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Here's a history of major game updates that greatly impact all builds. All of these should be considered "Mendoza lines," where any build that hasn't been updated since one of these updates needs to be viewed as potentially obsolete.
Aug 19th, 2013: Enhancement Pass (Update 19: Shadowfell Conspiracy)
Dec 17th, 2015: Level cap raised to 30 (Update 29)
Feb 2nd, 2017: Reaper difficulty (Update 34)