Overrated: Any overly optimized character (Sorcadin, Sorlock/Coffeelock, Padlock, Bear Totem Moon Druid, etc.). As much as I have many issues with 5e, this edition is so balanced, building a character like this for reasons beyond roleplaying is so dull. If you're new to 5e, give one of em a good run and get it out of your system. Beyond that, there's plenty of ability in just about any other build.
Underrated: Undying Warlock. So much that I wrote a guide in defense of it here:
http://www.giantitp.com/forums/showt...2#post23535972 I'm still peeved that Nerdarchy made a video about an entire party of Warlocks and still openly crapped on and left out the Undying.
Irrational Love: Any necromancy/dark themed class/subclass. Sorry, I have to channel my inner goth somehow.
Irrational Hate: Paladins. I didn't mind them until I played with a tyrannically Lawful Good Paladin player who insisted on immediatley killing any undead I created even when I tried to be as accommodating as possible (won't clog the board, will destroy after mission accomplished, etc.). From now on, I dread anyone in my group playing a Paladin when I plan on playing a necromancer, which is more often than not.