A toilet should disappear into the room and let everything else do the talking, and the number one reason that doesn't happen is people get hung up on the bowl shape and forget the seat is the part you actually touch every single day. Get the seat wrong, slow close, cheap plastic that yellows in a year, and you'll resent the whole fixture no matter how nice the tank looks.
This works in every bathroom you've got, honestly, from the tiny powder room off the hallway to the primary bath with the good tile, but where it really matters is small spaces, because a toilet that's too tall or too wide for the room makes everything feel cramped the second you walk in. Measure the rough in before you fall in love with anything, that's the number nobody tells you and it's the one that gets people stuck returning a thirty pound box up three flights of stairs. Where it's the wrong choice is anywhere you're trying to save money on the whole renovation, because this is not the place to go rock bottom, a bargain bin toilet with a thin glaze and a flush that needs two tries will cost you more in plumber visits than you saved. What separates a good one from a disappointing one comes down to the glaze and the flush mechanism more than the shape, a dense, bright vitreous china glaze stays easy to clean for years, while a thin one stains and dulls fast, and a good flush valve clears the bowl in one go instead of that embarrassing second pull everyone pretends not to notice. Check the seat hinges too, metal ones with a slow close hold up, plastic ones crack within a couple years and start sliding sideways, which my mother found out the hard way and complained about for a solid month.
Color wise, I'm not about to tell you to paint your toilet, but white is genuinely the easiest decision in this whole category, bright white against a colored wall, a warm wood vanity, or bold tile does more for the room than the toilet ever needs to. Biscuit and almond were everywhere in older houses and they fight with newer white fixtures nearby, so if you're matching an existing sink or tub, check the shade in daylight before you order anything.
Next to it, I'd put a small shelf or ledge in a wood tone for a plant or a little stack of good towels, something warm so the room doesn't read like a showroom.