Karbach's Hop Delusion and Community's Mosiac are both solid. I also love the Tupps DDH series.
There are a bunch of small batch series out there that are awesome. Community's Super Mosiac, Kush, and Medical Grade Haze are all really, really good. Spindletap makes one called Diamonds in My Mouth that's great.
There are so many options that it's really hard to nail down something like this. As for a flagship that's easily accessible & widely distributed, it's gotta be Yellow Rose.
Community Mosaic Tupps DDH series Cowtown's Resilience Butte County Proud IPA Deep Ellum Panhandler Independence Stash Buffalo Bayou More Cowbell 4th Tap Long Walk
Completely forgot PHP and Electric Jellyfish. I was only thinking of beers with some significant distribution currently. That is definitely the best IPA in Texas.