So one of my players asked, "What's a good class for beginners?" This is 5e, with lots of classes, so the game ramps slowly to keep you from being swamped with options. That said:
Fighters are still the best if you want simplicity. You'll have a few bonuses to keep track of that apply under certain conditions, but mostly what you get is lots of hit points.
Monks probably come next in complexity. You'll acquire points that you can spend on one-shot cool abilities, like making extra attacks or movement.
Rogues are probably next in complexity. Rogues have the ability to take extra actions and get bonuses to their attacks under certain conditions. If you're prone to analysis paralysis, you might find rogues easier than monks. On the other hand, if you have trouble keeping track of what's going on around your character, or remembering that under certain conditions you get special goodies, you might find the monk simpler.
Barbarians have a few abilities, like rage, that trigger a number of bonuses all at once. They also have some cool abilities that, like rogue abilities, only trigger under certain circumstances. That said, if you can keep on top of range of things that change when you turn you abilities off and on, the barbarian class can feel pretty simple to play. For organized people they can be even simpler than the monk and rogue.
Rangers, like rogues and barbarians, have conditional powers that kick in when the situation is right (like when facing a favored enemy or in a favored terrain). They also have a few spells.
Warlocks are probably the simplest of the spell-slinging classes to play, especially if you build them right. It's easy to create a warlock whose abilities are always on (for instance, always being able to read any writing, or always being able to detect the presence of magic). They also have much shorter spell lists. You might even be able to build a warlock who's less complex than a barbarian.
Paladins are more complex than warlocks. You've got your martial abilities, your spells, your divine powers, plus abilities that are always on. Since some powers are just like others with small tweaks, paladins are not for people who hate paying attention to details.
Sorcerers are a big jump up in complexity. They have shorter spell lists, but they also have points they can use to modify their spells; increasing the range and duration, for instance.
I think
bards come next. Bards come with lots of options for cool things they can do. Do you inspire your friends, cast a spell, distract the enemy, or heal the wounded? On the other hand, you'll always have something cool you can do. Not recommended for folks who suffer from analysis paralysis, they are perfect for people who like a wide menu of options to pick from.
Wizards are technically less complex mechanically than paladins, in my estimation, but the range of spells you can cast is the broadest of any class. Wizards are a great choice for players who have excellent memories or who don't mind flipping through the books to check on the details of a spell.
Finally, the class I consider the most complex is the
cleric. You've got the largest number of spells to pick from (especially at lower levels), plus additional abilities dictated by your pantheon. There's a lot of accounting with the cleric since you're tracking not just your spells but also your "channel divinity" powers. And your more likely to run across spells that are cast as reactions or bonus actions.
The
druid is like unto the cleric, especially once you start picking from among the various beasts you can turn into. Do you want the wolf who gets a bonus to attack when beside an ally, or giant spider who can climb walls, or the tiger who gets a special pounce attack?
All that said, one of 5e's virtues is that it ramps up slowly. It dribbles out the complexity over time, allowing you to digest each piece before adding another. So if you really want to play one of the more complicated classes, I say go for it. It might require a bit more effort on your part to create tools to help you get the most out of your PC, but better that, I think, than a character that bores you. :)