John and I recently moved back to the Seattle area after living in SF. We had sold our car upon moving to San Francisco, and haven't yet replaced it. But our friends' children were having a birthday party in Olympia and we thought it would be a great chance to hang out and catch up. So I set about snagging a car for the weekend. I initially checked out Avis, because we'd booked with them for our Hawaii trip, but thought I would look into Hertz as well. Here's what I noticed:
Hertz has a book-as-guest vs. a book-as-member option, clearly reminding users that they aren't necessarily logged in. Such a pet peeve to lose all my info entered upon log-in. Hertz tackles that here by reminding the user that they can login now. Avis just has a continue button, leading to the common mistake of entering all the info first and then getting the option to log-in, which may or may not clear things and reset forms.
Hertz smartly infers when an overnight drop-off is wanted, gives user option and info, Avis does not, halts process.
Breadcrumbs at top: Hertz wins again, for large clearly signposted breadcrumbs in the registration process, each with it's identifying marker. Avis: Small breadcrumbs, less obvious, and only a single label to tell which page you are on. If you need to go back in the process, you can tell exactly where with the Hertz breadcrumbs, but with Avis, you might need to guess.
Car lists: Hertz wins for me personally here because they show the cars and car types, in large open boxes that have all the detail I need plus clearly marked boxes that show me the difference in paying later vs. now. The Avis site is slightly more slickly designed here, but you have to manually select a car to see what it looks like and what seems like it was intended to be sleek and streamlined actually just turns into a wall of stat choices with no context. I preferred the more open layout of the Hertz list as I can see the cars easily by scrolling and don't have to open and close drop-downs.
Avis did just note that I'd stepped away from my session. I had a choice of whether or not to keep the session. Dunno what happens if it times out, but at least it signposts that the server may need to refresh information.
Things I'd like to see, but haven't interacted enough with the site to know: cookied information, so you can edit at any point in the registration process without losing ALL the entered info.
Anyway, this is just off the top of my head so far, not super in-depth. But I was trying to figure out why the Avis site wasn't appealing to me as much even though I have and had previous positive knowledge of Avis. (Avis rescued us in SF, and they are our rental car for Hawaii.) In the end, Hertz ended up winning me over for this car rental. Some of that was the cost, but some of it was also the design, and how easy they made it for me to compare prices.