First, ground meat is meh and it's not much cheaper then good meat.
I suggest either:
Skirt steak/flat iron steak/flank steak or Rib eye steaks.
Flank/ribeye are probably the best though.
If it's ribeye, take the outside of the ribeye (the part outside of the fat surrounding the center), and cook that seperate, eat it up, yum!! It's so freaking good, it's crazy to dilute it with taco ness.
The middle part though works great, bbq it and cut it up for yum tacos.
Next "bonus" is grilled onions, adds alot to the tacos, I recommend bell peppers as well (you can get em both ready in the same pan). It's delicious. A good salsa is key as well, then lettuce and tomatos (and for many cheese, but not me), and you have a mouth watering taco.
The meat though IS the key, a good taco needs good meat. It doesn't have to be beef though, Chicken tacos (I use thigh meat) are great as well (def wanna bbq the chicken though, you want the char chicken flavor), and fish tacos are great as well.
I heart tacos.
The BEST ever meat used to be a flank style kind of steak at safeway, but it was a special way they cut it, into a long strip about 4-5 inches wide) that was amazing. It was so good but it hasn't been available for years. I have NEVER been able to find a cut like that since....but it was freaking insanely good for tacos. I miss them so much.