Hoping for advice/info on truck for towing
 

I joined this forum to learn about trucks so I could make a better decision about my upcoming truck purchase. I want to get a truck and horse trailer and have been researching them for about a month. I'm looking at getting a GN 2-3 horse trailer. Safety and reliability are very important to me. So far I have figured out that I should probably get a 3/4 ton truck, crew cab, regular bed and 4WD. I can't afford new, so looking for used with a budget not to exceed $30K.
There are so many other options.

Which make: Ford, Chevy/GMC or Ram?
Gas or diesel?
Are leased or fleet vehicles good or bad?
What should max miles be? Thinking 60K at moment.

What other things should I be considering?

This will be my second vehicle, not everyday driving vehicle. I live in central Texas and will tow 100-300 miles over flat to moderate hills.

Thanks for help in advance.

What is your price range?

I think without a doubt you should look for a 2004-2006 GMC/Chevy with the 6.6L duramax.

If you can swing it, go with a 1 ton dually. We use our trucks for hauling horses and the dually is AMAZING when dealing with the horses weight shifting... You never feel it. Our tow vehicles have been a 2006 GMC 2500HD Duramax that wasn't big enough for a 3horse slant, 2011 F350 and now a 2015 F350 Dually