I'm a former Starbucks barista. I tried black coffee from 4 fast-food chains, and 2 were surprisingly good.

As a former barista and self-proclaimed coffee connoisseur, I set out to taste test black coffees from Sonic, Wendy's, Burger King, and McDonald's.

• As a former Starbucks barista, I tried black coffee from four fast-food chains to find the best one.
• McDonald's and Wendy's were worth coming back for — I enjoyed the flavors of both.
• Burger King was mediocre but drinkable, and Sonic ended up being the only one that fell short.

Despite being a former Starbucks barista and self-proclaimed coffee connoisseur, I have a soft spot for crappy cups of joe. 

I'm talking about the coffee you get from gas stations on a road trip, funeral homes with questionable powdered "creamer," and greasy-spoon diner counters on Sunday mornings.

Like these spots, fast-food chains aren't necessarily known for their blends, so I ordered a small black coffee from McDonald's, Wendy's, Burger King, and Sonic to see which has the best.

I then ranked each coffee based on five categories: sweetness/bitterness, body, acidity, flavors, and finish.

Sonic was the only chain I wouldn't order from again

Sonic's breakfast menu has lots of hits, but coffee isn't one of them — unless you're a die-hard Keurig fan who likes the familiarity of Green Mountain coffee.

I ordered this later in the day, which worked in my favor because the employee had to brew a fresh pot. But the little hope I had was dashed after a few sips.

Maybe I just got a bad batch, but I thought Sonic's coffee was poorly extracted (the process of steeping the grounds in water), slightly bitter, and just overall disappointing.

If Sonic was your only choice for coffee, I'd suggest just not getting coffee. 

Burger King's coffee was solidly mediocre

The temperature of Burger King's coffee was closer to warm than hot when I got it, but it was well-extracted.

With chocolate on the nose and notes of molasses, it was more sweet than bitter. Although the overall flavor was pleasant, it was slightly more acidic than the others, which made it difficult to drink too much of it.

I probably would've enjoyed it more if it were fresher and hotter. 

If it was the only option, I'd order it again. But I wouldn't seek it out.

I was nervous to try Wendy's, but it was the biggest surprise of the bunch

Wendy's describes its coffee as a medium roast, but it tasted more like a light roast to me. 

It's pretty bitter, which I didn't think was a bad thing — it worked with the overall flavor.

Temperature-wise, it was hot. I wound up running an errand before it cooled enough to drink, but once it did, it was delightful.

It had very little acidity, which made it easier to drink. Although the flavor profile was more bitter than sweet, it had soft floral and herbal notes on the nose and tongue.

I ended up trying the same order at three different Wendy's. At one location, the extraction level was weak, at another, it was well-steeped and flavorful.

Even with this slight mark against it, I'd order this again — and not just if it was the only option.  

Overall, McDonald's had my favorite cup

The best part of this whole experience was being able to recreate one of my favorite John Mulaney bits by going through the McDonald's drive-thru and ordering "one black coffee."

But the coffee wasn't bad either. McDonald's, and its McCafé line, is probably the fast-food chain with the most coffee cred. 

Its coffee had a deep-chocolate nose and was on the sweet end of the sweet/bitter spectrum. The blend had very low acidity and was well-extracted.

Out of the four coffees I tried, this had the best mouthfeel.

McDonald's coffee is famously hot — there was even a lawsuit in the 1990s involving the safety of its temperature. But that worked well for me since it was about 20 degrees Fahrenheit outside when I ordered it. By the time I got home, it was perfect.

I'd happily order this again.