Soy sauce, BBQ sauce, A1, Lagonma chili crisp sauce. All excellent.
I decided to try honey mustard on rice today. Another triumph.
Haven’t tried maple syrup, ketchup or mayo yet.
Colman’s English Mustard.
I don’t think ketchup tastes very good on rice, but my kids do.
Ketchup, I was gonna say. Then mustard.
Add some ground beef to it and then the mustard. That was dinner for my mom quite often when we were growing up.
Is pickle relish a condiment? If so, then that’s my vote.
Xmas eve I made some insanely great cocktail sauce to serve with shrimp cocktail. I used some of the leftover sauce on rice and it was great.
I also made a snack of Banana and Cocktail Sauce. I loved it; the sweet/spicy thing was awesome, but nobody else was willing to try it.
You can eat rice and horseradish sauce if you’d like but leave me out of it.
In Japan, omuraisu is a common “western-style” dish. It’s an omelette filled with ketchup fried rice and is quite delicious.
As far as condiments that probably wouldn’t go well with rice, I would say hot dog relish or tartar sauce.
Ketchup on rice sounds so awful to me but we have an exchange student from Ukraine at our house and he loves it. He puts mayonnaise on his hot dogs and microwaves his cereal as well, but he never complains about our cooking so we appreciate that.
Chocolate syrup & sprinkles.
Mint jelly.
Soy and teriyaki sauce are the only condiments that belong on rice.
Gravy is fine, so is a nice broth. But ketchup or mustard? Yuck!
It’s hard to imagine anything that would not go with rice. It has a mild neutral flavor. It is fantastic as a dessert like sticky rice with mango and sweetened coconut milk. Any of the tomato based sauces, even catsup should be fine, that is the basis for Spanish rice. Pickles - sure, just think of kimchee.
Dennis
My Dad said when he was young, they used to sprinkle cocoa powder over the leftover rice and eat it like cereal.
All rice has a subtle sweetness to it, brought out the more you chew it. Long grain less so, and high quality short grain like Nishiki much more prominent. And then, there’s mochi or sweet rice that is noticeably sweet, more so when pounded.
I suspect rice cakes taste bland because of the high pressure and steam required to puff the rice removes the natural sweetness.
My wife eats rice with grape jelly.
I would imagine that hot sauce and rice might not be particularly good, unless you’re the type that just likes hot sauce by itself.
BeeGee’s Quick Mexican Rice
Put one T of oil in a sauce pan and heat it up. Add 1 c dry rice and brown it being careful not to burn. Add 1 small can Herdez or Pato hot sauce to a two cup measuring cup. Add beef or chicken base to the cup to make 2 full cups liquid and hot sauce. Add to saucepan, bring to boil, and reduce heat. Cover tightly, cook til done about 20 minutes.
Maybe Nutella.
Guilty as charged. I think ketchup on rice is disgusting, but I’ve eaten rice with only hot sauce on it, so I guess who am I to judge? 
Or crushed pepper flakes. But what’s not to like–a bit of vinegar tang, a bit of spice, a bit of other flavors. Yum!
One of my go-to comfort food meals is rice with (good) ranch dressing, chopped up hard boiled eggs and either shredded Italian cheese blend or feta. I call it “white bowl”. 
Sriracha & rice is pretty common. And, if the definitions are loose enough, a Mexican salsa goes well with rice.