I find it hilarious how good Dimir's creatures are for limited.
Unrelated, Doom Whisperer is just the kind of magic card you look at and say "Wut?" And then reread looking for a missing word or line of text.
I'm pretty biased towards dimir/izzet guilds, and while I agree with what you're saying, I think the boros/selesnya/golgari stuff all looks just as solid right now. Everything seems a bit stronger then normal, but that's cause there are a bunch of gold cards that are naturally higher power level. Especially in comparison to the m19 we've been drafting. Something like Conclave Guildmage (GW, 2/2, G, T: Your creatures gain trample. 5W, T: Create a 2/2 elf knight with vigilance) would be pretty close to a bomb in m19, as a random example. Or, the Ochran Assasin (1GB, 1/1, deathtouch, All creatures must block it) is basically what declare dominance did, in a 3 drop creature.
I think izzet, on the surface, looks the weakest so far. But, that's often true of R/U 'spells matter' decks in any limited format. Or, they need a certain amount of pieces before they are good. Despite that, from an enjoyment perspective, I'm looking forward to playing Izzet the most
That's easily my favorite guild.