That's right, I actually made an account here to talk to people about stuff, lol. But I'll try to chip in since I guess people value my input. My opinion probably isn't as well-informed as that of others, but...
Aquaman's a straight 5-5. Aquaman has the advantage in overall combo damage output but DS checks Aquaman's ability to play a mindless FTD zoning game, as reversal Quick Fire punishes FTD for free. MB Quick Fire is guaranteed if his trait is down. DS can also play solid footsies with Aquaman as long as you don't jump predictably.
Doomsday as a 5-5 is one of the biggest match-up misconceptions imo, it's at least 6-4 Doomsday and the primary reason I don't exclusively play DS. None of the Florida Doomsdays disagree with me on this. If you're 100% consistent on blowing up Doomsday's wakeup options (which is very possible) then it's not as bad, but DS has very little means to control the pace of the match, especially if Doomsday gets trait up. One blocked/whiffed set of gun shots and Doomsday gets within range to threaten you in one forward dash. It's not impossible to shut down Doomsday's momentum, but every option you have in any given situation carries such a high risk for the fact that d1 xx Earth Shaker does as much damage as 2-3 good reads on gun shots. Never mind the fact that DS doesn't have a spammable normal to lock Doomsday down during trait.
Green Lantern is... not a fun match-up at all. I used to believe it was a 5-5, possibly 6-4 in DS's favor, but the overall exchange of damage in zoning between the two characters when making good reads is often in GL's favor. And once he gets within mid-range you have to start making incredibly bold decisions just to gain an advantage. Gun shots at the wrong range are easily punishable by reversal lift, and b13 ensures you basically can't play footsies with GL at all. You have to give him reason to pause so you can hopefully dash in and start some f23 frame trap pressure. But if the GL player is both competent and confident you won't get many opportunities like this at all; you have to boldly guess right and just hope for the best. DS is also one of the few characters who gets almost entirely screwed by b13 xx db2. The only way to get out of the string without taking a bad trade is to a) get really good at backdashing the second hit of b13, which is an obscenely small window, or b) MB f3 in the small gap between b13 and db2. This is actually a pretty great punish for the series, but the window for both options is very tight and the easier option costs meter, which in turn means you can't spend meter recklessly. Ultimately, the point is that GL's job is infinitely easier than yours in the match-up, and that doesn't seem like a 5-5 to me.
MMH is actually a solid 5-5, which is probably one of DS's more desirable features. I played a bunch of matches with Jupiter at Civil War this past weekend, and after getting acquainted with all that character's BS it became evident to me that DS can keep MMH honest at long range easily. This means he has to gamble with overhead teleports to counter gun shots and get an easy in, but if he does it at a bad time you can blow it up with MB b3 and force him into the same situation. You can still get wrecked if he gets too close/puts you in the corner, but a well-placed Sword Flip can give you the breathing room you need to apply your zoning game.
Zod is definitely not a 5-5. Similar to Doomsday, this is at least 6-4 in Zod's favor and one of DS's worst match-ups imo. DS has ways of checking Zod's trait activations with good reads but you can't play footsies with Zod at all and once trait is out you're forced to exercise godlike blocking or taking high-risk gambles to keep him from hurting you badly. It's entirely possible I just don't have enough experience with the match-up but it's never been pleasant in my experience.
I have some more input to give for other match-ups, but I'll settle in on it later. And again, I operate mostly on Theory Fighter and some degree of match-up experience, but I feel like I've played enough really strong players to make fair judgments here and there. Some of DS's match-ups are harder than I think a lot of people imagine, but he also has a lot more control in other ones.