I would use scallions

Either but the scallions would be prettier.

I prefer reds in potato salad, better texture than russets. Both come from more places than just Idaho.

Green onions are colorful but taste-wise I prefer mild red onions. Maybe a little of both. Don't forget to add a little Dijon mustard if that's a flavor you enjoy.

Edit to add:

Please send me some when you're done. Perfect for a BBQ or other July 4th events.

I always use red potatoes and generally have purple onions on hand. Sometimes I sprinkle a little bit of green onions on top.

Sweet onion.

I use red potatoes, preferably but will use others. Sweet onion if I have on hand but will use red or yellow, too.......Just finished making the base for the potato salad......red potatoes, sweet onion and celery, marinating in some Italian dressing. Will add the egg and mayo tomorrow. Maybe even some pimento and olives. Now on to the baked beans. :-)))

Red/purple onions.

I don't care what onions you put in, just share the results with me. ☺

I would use red onion with the red potatoes which are a little sweeter and creamier than an Idaho potato.

I always use red potatoes and green onions. The whole thing. White and green parts.

Red onions....but I'll eat it regardless of what onion you use

I like a creamier potato salad so used to cook russets longer than most but reserved some that were just tender. I added most of the ingredients immediately after draining. It would result in a soft salad to which after it cooled I would add the reserved potatoes. I used any onions that were available in the house. Never used red because I seldom had them and I thought they would bleed into the salad leaving red streaks. Red potatoes because unless cooked too long do not mush were reserved for other things.

Never heard of green onions in potato salad. I switched to using red potatoes a few years ago and I use yellow onions.

I use green onion tops because DH is sensitive to onion and the onion tops are the only way I can get the flavour without upsetting DH’s tummy. Before he also became sensitive to garlic, I also liked to add a shot of ranch dressing to the mayo, as well as Dijon mustard (which I still use).

I prefer the green onions when I am serving onion in a dish raw because it doesn't have such an intense pungency as other raw onions do.

Use whatever you like best. I'm a fan of the purple/red onion myself. I never use red potatoes myself. And most people who do never cook them enough and I'm not a fan of crunchy potato potatoes in salad. But I'm also a fan of celery and lots of egg in my potato salad too. It's all personal preference. There's no "right" way. Reminds me of a favorite Justin Wilson line "People ask me all the time what kind of wine should you drink with that dish? I say, 'What kind you GOT?'"

Ah, 4th of July! Two of my favorite foods for that day are potato salad and cole slaw and don't skimp on the vinegar. Oh, maybe someone will make deviled eggs, too.

For those that like a crunch like celery in the salad but are making it for a crowd that may or may not like it, try dicing a Granny Smith Apple instead and using celery seed in place of celery. Most will like it but can’t detect what it is.

We find that the onion can be over powering, and for that reason add it just before serving. Maybe the scallions would be just the ticket. I have chives in my garden, think I will try that in lieu of onion today.

I also use whatever I have on hand, but usually it is the red onions, because I almost always have them, but I have also used green or yellow onions. The red onions don't "bleed" and change the color. They do add a little more color to the potato salad, just as they are.

Potato salad is one thing that no two people make alike. I make mine as sort of a combo of how my mother and older sister made theirs. My sister added stuffed green olives. I add bacon. I make a dressing of mayo and a little spicy mustard and celery seed, thinned with pickle juice. And never anything but Claussen dills. Of course, onion, celery and eggs...sometimes bell pepper. Now I have to make some!

Happy Fourth of July!! Thank you all for your responses. I boiled the potatoes & eggs yesterday. Going to get off here & put the potato salad together. Have decided on using the sweet onion. Will dress the salad with mayo, Ranch dressing with a shot of yellow mustard. My husband will have a grilled steak, I will have grilled salmon, along with corn on the cob, cucumber tomato salad & of course potato salad. And have rainbow sherbet for later on.

As long as there is a finely diced pickle and a little mustard for zing, it doesn't matter which potatoes or onions you use. :)

Sorry no pickles for me. My SIL turned me onto adding a bit of vinegar with the mustard. I just finished ours and as always it brings me back to a story my MIL told. WAAAY back in the day her mom would ask her dad "what do you want for lunch" and he would replay 'Oh something easy like potato salad'!! NOTHING fast easy or simple about making potato salad. But I gotta say having just made enough for DH and me--it really wasn't that big a deal. LOL

Have never used anything but scallions/green onions in potato salad! Bulb onions of any color are too strongly onion flavored and overwhelm the salad. I want to taste the other ingredients.......not just the onions :-) And I use Yukon Gold potatoes.....sometimes with the skins, sometimes not. They hold up well in salad - never mushy, never too hard.

I don't like pickles in my salads so omit them. Sometimes I do add celery, often I just skip it. Always hard boiled eggs, always dijon mustard, usually some curry powder and plenty of other seasonings. And only enough mayo to hold it all together.

I don't care for many versions of potato salad other than my own :-) Most are either way too bland or too pickle-y or onion-y.