How about TEC XT? Comes in both Sanded and Unsanded versions (for most colors), and is supposed to be more stain resistant and mold and mildew resistant than other cement-based grouts. It does require a longer cure time 7-10 days before getting wet or sealing (doesn't need to be sealed, but can be, with a solvent-based sealer, which we did when we sealed the marble and trav tile in both bathrooms). I sealed it in the MB at 7 days because I needed that bathroom functional "now" LOL.
It also requires a drier clean-up (just wring sponge out well when wiping off excess grout, according to the rep with whom I spoke during my grout "research"--there's a video you can watch, too). It's a little stickier than the reg TEC grout, so you might need a bit more elbow grease to remove grout haze, but that's about it.
We used the Bright White for the field tile in both upstairs baths (used the reg TEC in Bright White for our kitchen and guest bathroom since the XT either wasn't around then or we just didn't know about it at the time). We used both the Sanded and the Unsanded. The Unsanded is a bit whiter than the Sanded (because the sanded has actual grains of sand, which I'm sure you know), but both seem white enough. We used a very glossy, very white, Porcelanosa large format tile in the MB. Our grout lines are very tight, except for the White Thassos mosaic/border (which came pre-mounted on mesh), and the Unsanded worked very well. We also used it (in Almond) with the split faced trav mosaic in the hall bath which had practically non-existent grout lines in spots.
Of course, when I say "we" used any of these products, I mean our wonderful tile guys used them for us!
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This kitchen has Corian Quartz London Sky counters and Mapei Warm Gray Grout on wall tile.
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