MedStar does Fort Worth and 14 other cities. Correct, they aren't currently looking for Paramedics, but give it a week or two and I guarantee they will.
AMR Arlington... they hire at times but are hard to get on with (Not due to being strict, but due to a good boy type system and people staying on) The medics I know there are content with it. However, you're pretty much AFD's b****.
CareFlite does ground 911 in Johnson County, Segoville and Balch Springs, but you'd be hard pressed getting in one of those off the bat and are more likely to get stuck in the Dallas operations doing transfers.
Cooks, I hear good about, pays decent, Paramedics can actually do things in their ER, and I have a former classmate that works in the ER.
AMR has a Dallas branch that does mainly IFT, but also has 911 in Collin County and Hunt County, again... hard to get in on due to medics staying forever.
Rockwall County... pay is meh, but the friend I have there enjoys it, and they treat you rather well.
Wise County... never hires. Ever. Ever never ever.
Lone Star EMS, in Dallas as a transfer company, has a great reputation from its employees.
Granbury/Hood county, someone on this forum works there and he seems to enjoy it, but again, them hiring appears to be a rarity.
Then a bunch of small IFT agencies in Dallas. MedStar has Tarrant county locked down, and AMR has Arlington locked down, so all the other transfer agencies are relegated to the Dallas side. All the other 911's not named are fire based, and tend to be on the Dallas side of DFW.