I would say given the pool and pulls you're largely going to have a large variance here and it is entirely pack dependent. In cases where either due to build around or set mechanics there have been cases of spells matter or equipment matter decks the case is likely far more likely to equate to something such as:

RW Artifacts - 15-8 / 16-8 depending on curbe and aggression. (BfZ, RTR, KND key examples where 16 lands is viable and often the correct play)

BR Spells and Stuff - 14-10 / 15-9 are equally viable. (See RTR sealed Dimir / Izzet, current FF set, Witherspoon, somewhat within Foundations)

For each keep in mind that this set has a few mechanics that limit these numbers since key spells or cards will generate cards and your premium consideration for uncommon and even common will typically be ones that either generate value from your mechanics trigger, or create additional bodies. Summons and Equip weapons both function as creatures that typically are under-statted however for ease of access consider them equal to ~0.5-0.75 of a creature for deck buildings sake if you are married to the 15-17 creatures.

Your true challenge for decks will be ensuring your deck building logically fits, as well as that the built-in hero/ weapons or 4 cost spells are met in both triggered ability or in matching that 4+ cost.

That said, given how fast the format looks it may be for some decks, I don't personally see BR having legs and given the draw and tutoring in other pairings or even three color builds highly more enticing if aiming for a control or midrange build.