We use Grubhub, Caviar, Amazon, & Postmates.  They all have their pluses and minuses.  Grubhub has the highest fees, but they do well promoting their service and we tend to have the highest volume from them.  Their back office is nice because you can update your entire menu from anywhere.  The biggest issue I have had with them is getting the delivery drivers here on time during busy rush times.  After many complaints their customer service team things have gotten better, but we tend to wait before firing their orders because of this.  All in all Grubhub has some of the best features (back office, promotions), but some of the worst problems (price, on time delivery).

Caviar and Amazon are good and the fees are a bit lower, but we don't do anywhere near the volume we do with Grubhub.  Rarely have issue with getting drivers here on time.  I just wish their marketing and promotions we a little more on point like Grubhub.  Also changing the menu is a hassle as you don't have direct access to this--you have to submit a tedious form or wait on hold to talk to someone live.  We would include a lot more items if this back office feature was available.

Postmates might turn out to be my favorite.  We haven't been with them for long, but their fees are much lower than Grubhub, give you the ability to edit your own menu, and you can set the prices differently than your normal menu so you can make up some of the percentage they take.  The other services put in the contract that your prices must match your in-house menu.  Their back office is very easy to navigate and has all the functions that Grubhub has except you can't attach pictures to each menu item yourself.  Also the drivers have shown up in a timely manner.  You have the ability to set your own promotions and like Grubhub we are able to have our full menu updated daily.  I also like their tablet setup the best and the data and reports that it gives you at the end of the day.  

Haven't partnered w/ doordash, but I am wary of them based on the orders they have placed from us so far.  They have some version of our menu posted, but it tends to be outdated.  Read some reviews of them and it has not been impressive thus far so we'll see if they are still around in a year or two.