got a question for ya

who do u think is the better duelist : the one with like a 3000 rating who only uses t1 decks or the duelist who has like a 300 rating but has a custom made deck

rating honestly doesnt mater

well using a custom deck that is losing more games than its winning, clearly needs improvement. while someone who uses a t1 all the time in ranked, is looking for competitive games.
To be a Good Duellist you need to be able to play on a competive level, understand what is current teir and current meta, how to side and be prepared for such things, using a custom deck or a t1 deck but you need to also have a good understanding of deck construction and being able to bring out potential in decks.
But someone who refuses to play competively because omg T1 is op, when in the current Format part from the odd teir deck, most are only Teir because of consistency of what they do you need to understand Competive play vs normal yugioh is like 2 different games

Gabriel i might only use tier 1 decks but give me a custom deck i can own as well with it as i do with a tier 1. I simply suck at deck constructing :P not everyone is awesome like you at it and they prefer making simple easy tier 1 decks.

custom deck

The deck is very important... But think about this: What is a good duelist with a weak deck? Now look at the other side of the coin... What is a duelist without talent with a top deck? The point is this: Both the deck as the duelist are important and if you mean the competitive side, you should be prepared to face the current decks...