What I recall about [turbo pascal] (maybe incorrectly) is that it was easy to read, indenting things and using colored fonts to make it easier to see what went with what.
I was hoping there was something similar (and free) for C.
Doesn't the Arduino IDE do that? It has keyword highlighting rather than true syntax coloring, and a rather "fixed" idea of correct formatting/indenting, but it's got the basics.
The Arduino IDE does a number of non-editing related things "behind the scenes", including function prototype creation and library path derivation. Using another IDE will require some replacement for those capabilities, either manual effort or special hooks.
There was a Turbo-C at one time (from Borland, the same company that brought you Turbo-Pascal.) It does PC programs only, though. If you're interested in writing C programs for a PC environment, there are a separate set of IDEs that you might find useful, including a FREE DOWNLOAD of an old version of Turbo-C. (It looks like it's a hopelessly ancient DOS program to me, but YMMV.)
I decided to try Visual Studio Community. I look forward to trying it some time in 2018, when it finishes installing.
For all the complaints about the Arduino IDE, it's about 1/10th the size and 1/10th the install time and effort compared to a bunch of near competitors. I've only actually measured Atmel Studio and Microchip MPLAB-X, but they both ran 3-5 GB in size. (the AS7 install is a big improvement over the AS6 install. Now it remembers that you accepted the license(s), instead of needing your input every 30 minutes or so. So you can mostly start it up and leave it...)