TBH, pretty much all my best lead melodies ever have been up/down arpeggios to start, then I change the length of the notes and remove some (for example maybe the 3rd in what starts as an arpeggio over the 7th chord) to make it a bit less obvious. When you’re trying to make that mainline EDM stuff, I bear in mind what they taught me in business writing - KISS - which stands for Keep It Simple, Stupid. If you want to get fancy, start the arpeggio on not the root note of your chord and make your melody an inversion of the chord you’re playing. People think I know jazz theory or something when I do that.
As far as sounds go, I either use the Uni-Pizz JS-Y preset from any Korg M-1 VST, or keep it a simple saw/square lead, maybe some (and I mean SOME, not A TON OF) modulation to keep it moving (FM, vibrato, etc). Pretty much any functioning synth will give you a passable lead sound. What I notice with a lot of the modern stuff I listen to is that the lead is almost always just a supersaw with a crapload of effects on it. So if you can make a supersaw, or recognize one in the presets of the synths you have (and @bfk I know you have Harmor which is an absolute supersaw machine) then you are pretty much in business soundwise.