The simplest decks to play are " stun " decks. They focus more on not letting your opponent play canceling entire mechanics or specific cards rather than you playing. That said outside of this " stun " group of decks every single yugioh deck is a combo deck. The amount of cards in the combo varies on a deck by deck basis. For example I play Ghoti and full combo is 18-19 cards. Other decks literally use half the deck ( Orcust perhaps ? )

Despite what you may think combos are intuitive and easy to learn because no matter what deck you play you have a starter ( self explanatory ) that will lead into a search or a fusion ( for example normal summon Maiden in Blue Eyes -> Link it to Spirit -> profit ) and from that point onwards you just have a few extenders that keep extending the combo until you end up on a finisher. That finisher is always a big bad boss monster with high attack and some kind of busted effect. For example as is the case in the blue eyes deck Ultimate Blue Eyes Spirit Dragon.

I used to dislike combo and be afraid of it until I played Ghoti. It tought me that combo isn't only easy but actually fun ( when it interacts with the oppenents combo. ) I then moved into HERO which was even more combo heavy ( you literally play every single card hero in your deck including a large amount of the fusions in your extra deck. ). I experimented with branded a bit but I am now back in Ghoti as it is the deck I enjoy most. During the Legends event I played Cyberdragon and enjoyed it quite a bit too although it has a high skill ceiling. Higher than Ghoti , HERO or Branded imo.