KoTH is the best mode.
It's the fairest, equally balanced since both sides are required to be Offense & Defense to win the round. Rewards adaption and teamwork.
Offense on Cap/Payload is the most braindead and probably highest win-rate mode. There's no way to "wander", so Offense can eventually get a push sync'd even by accident. Also can end rounds early by getting off 1 good push and capping which avoids dumb mistakes as the round drags on.
Being a Defender is worst, no matter if payload or capture points. Ease of players to wander around and leave the objective site are too high. Requires more teamwork and for longer duration. Easy to have a misplay since you're required to defend for so long.
I've narrowed down my SoloQ woes to having to be Defense as 1st game, practically always. New Strat is to dodge my 1st game if it's a defense round. After 1st game you get settled in with a team and also benefit from Consecutive Round XP, but as 1st game of the session I'm avoiding Defense now.
I like how the matchmaker seems to give both teams a chance at both offense and defense with payload maps though. Like if eveyone stays in the game, you should get 2 games with the same people, where in the first game, you are on Offense, in say, King's Row, and in the 2nd, you are on Defense. I like that a lot. I enjoy King of the Hill because Mei is my most played character and she really excells there, but a friend I sometimes play with is Tracer and he absolutely hates them. Obviously you can't just latch onto one hero though. I think Lucio is a god in all modes tbo. I feel crippled without a Lucio. I guarantee his ult will be nerfed one day.
Keep in mind that Black Hole thingy isn't real CC. I got hit with it on a final push as Reaper last night mid-ult and all it did was make me move super erratically while I gunned down their team
If the enemy team isn't offering up free damage or easy charge then Zarya just turns into a kinda lame support, so just like any character there are matchups where you really are going to suffer trying to wedge her in there.
Roadhog and D.Va are definitely my go-to fatties right now, because they fall into that same playstyle I love of just skirmishing and causing havok. Peek around corners, flank when you can (or just fly to crazy places), repeat. I can't accomplish anything with Rein or Winston for the life of me. Also pretty terrible and Junkrat which doesn't surprise me considering Demo was one of my worst classes in TF2
You might not be playing Junkrat as aggressively as you should be. Yes, there are plenty of times where it's best to lob grenades from relative safety, but I actually find myself going in midrange-close more often than not. Direct hit grenades are insane. I can chase down over half the classes in the game and kill them before they can react because if they do react I just throw a mine, detonate in mid air and send us flying in opposite directions. I consistently get gold medals for Junkrat on damage and objective kills and I am very aggressive. I've found a few golden spots on certain maps where I can lob grenades from safety and guarantee to do damage because the enemy team has to be where the grenades are landing or they are losing, but other than those spots, I am being very aggressive.
A good example of this is on Lijang Tower. The best part about being aggressive with Junkrat is that you get a lot of kills just from dying. So if you manage to go in close and kill 1 person, severely damage another, and then die and kill another, you've done your team a big favor. And yes, good players can usually avoid his deathnades, but not always, they blow up really fast after death and sometimes there is nothing they can do to avoid being hit by them So yeah, don't be afraid to be aggressive. Scrubs will tell you Junkrat takes no skill, they are very wrong. Practise the art of mid air mine detonations and you'll do great. And don't forget to utilise Junkrat's insane mobility via the concussion mine blast. If you jump over it and detonate it at the right time (e.g. not directly above it but a little further ahead) you will go flying. Doing that allows you to actually be a really good flanker as well.
Also, pro tip regarding his Rip Tire is to set it off directly against a wall, it reduces how loud the noise is that broadcasts to the enemy team that you are thowing a tire, and then just let it sit there stalling against that wall for a second or two (if you have the time), this will almost muffle it completely and allow you to take the enemy team unaware. Just like Tracer has routes on maps, so does Junkrat's tire. I've learned some really crazy, creative routes with the tire just by practising. I get triple and quad kills at least 33% of the time I use a Rip Tire. 2nd pro tip, go into options and select Junkrat and turn his tire auto climb walls on, makes it much easier. My tire is like a cracked out genji.