Do you lean towards staples or look for flavourful cards?

[Aetherium Slinky]

Some cards are really powerful: Rhystic Study for example. Does your deck always have those staples or do you try to find cards that do the same thing but fit your theme, have in-built synergies or some other factors that make the cards really cool? This question is in the context of "you've already included all the necessary cards for that archetype (=your blink deck already has Mulldrifter) but you still have a few card slots left" - how do you fill those slots? Does Rhystic Study go in or is there a situation where you would pick something else and why?

EDIT: I like to add all the good flavourful cards first, then look for a few obscure, sub-optimal ones and fill the rest in with staples. Staples are staples for a reason: they always do their job effectively and usually add a layer of consistency to my decks. Hence I feel like it's a good thing to add them for the sake of consistent game play.

[Bonethousand]

I definitely long for a time when EDH was slower; it reminds me of why I got into Magic in the first place. Because of this, I love including the cards I have sentimental attachment to or the cards that feel cool (aesthetics, uniqueness, jank); however, as I play more and the cardpool evolves, I find I just end up putting more staples in to keep up with the turn pacing. I feel bad when I look over my piles of unused cards, but sometimes you're holding Angelic Ascension and you really wish you could just play a Swords to Plowshares on turn 4 while also casting your commander.

[Morganator 2.0]

I gravitate towards staples. Those cards are tried and true so they are more likely to be beneficial to the deck. I will use a more niche card if it's able to fill a function better than a staple would. For example, I recently came across Icatian Moneychanger from one of the worst sets, Fallen Empires. Pretty crummy card... but it does let me play Licia, Sanguine Tribune on turn 3. There aren't a lot of mana ramp or lifegain cards that can give that result.

[Valmias]

I gravitate towards staples. Those cards are tried and true so they are more likely to be beneficial to the deck. I will use a more niche card if it's able to fill a function better than a staple would. Fir example, I recently came across Icatian Moneychanger from one of the worst sets, Fallen Empires. Pretty crummy card... but it does let me play Licia, Sanguine Tribune on turn 3. There aren't a lot of mana ramp or lifegain cards that can give that result.

Oh wow, that Moneychanger use is beautiful. And I think that is why I tend toward the more unique cards over the staples. Staples will give a good, consistent experience, but the jankier options can really spike in apparent strength if the deck is built for them. The adage that I build by is "More words equals more power", since the more complex a card's effect is, the more chance there was for the designers to create (possibly unplanned) alternative functionality.

[robort]

I try to stray away from homogenization and try to create something uniquely different. With a such a big pool of cards that can be used so that means there are so many different things I can create without actually having to use the same card. However using cheap staples like per examples sol ring, arcane signet, command tower, and exotic orchard is about the normal I would say of using staples. Some of the lands I choose are staples  but lands like cable coffers where I only run 1 in 1 deck and nothing more. 1 or 2 decks run the tutors while the other decks I own just don't have tutors. I aim to try to make every deck as unique as possible while just running the cheaper staples.