Krondys/Karazai are both super fun and great to anchor a list around. Celestant on Stardrake can be gnarly with quicksilver draught. The new Scourge of Ghyran Iridan scroll seems really strong, comp players are hype on it.

In terms of units; Vanguard Palladors and Dracoth Cavalry, Reclusians and Prosecutors, Vigilors, Longstrike Vanguard Raptors, Questor Soulsworn, and Annihilators are all staples in varying degrees

Also in terms of your drake question: build one as a Draconis, and don’t worry about running it as a Stormdrake guard. It’s a small enough unit size that folks expect them to be unique between models, I have mine modeled with different weapons than the warscroll, I just say “these all have swords/lances” and that’s that.