I've rented from all kinds of companies. Unless you're really pinching pennies, just skip the likes of Budget, Thrifty, and Dollar. Either the cars are pretty bad or the service is bad. Hertz is decent, but in my personal experience it's hit or miss about half the time. Only National has been consistently great—except for one time when a guy at the pickup location was a bit odd—the cars have always been in good shape too. And with National, if you have a card like the CSR, you can pay a flat fee to pick a car from the Executive Area. I've been to quite a few locations that had entry-level or mid-tier BBA models. Plus there's no line to wait in, which is great for introverts. And most rental car counters are no more efficient than the DMV...
At first I tried Priceline, Expedia, or my own company's code to find deals, but found them not very reliable. The most reliable approach is to find a good code. I won't share codes here, so they don't get overused and stop working. Hint: make good use of Reddit, and make good use of ChatGPT and other AI tools (you'll need a few back-and-forths). If you really can't find one, feel free to DM me and I'll share as appropriate.
The core takeaway is really just one thing: National's consistency and the car-selection experience in the Executive Area are what set it clearly a notch above the likes of Budget and Thrifty. It's also true that not having to queue at the counter is a plus for introverts—with many rental companies, just standing in line can eat up half an hour. As for the code determining the price, that's indeed far more reliable than blindly hunting around on comparison sites, but the codes that actually work often come with eligibility restrictions, and few are usable long term.