Currently I'm using Linksys EA6900 with latest FreshTomato. Tomato is great, but its based on a bit antique kernel 2.6. So I'm testing alternative solutions on spare routers that I have.
On Netgear WNDR4500v1 I installed DD-WRT with kernel 3.10, and on HomeHub5 I installed OpenWRT 19.07.
DD-WRT is not the topic here, so I won't complain about the mess in options there, poor intuitiveness of the Web UI etc.
But, as I spent whole last weekend installing and configuring OpenWRT on the Home Hub 5, I feel that time was simply wasted.
I have no time to write about every problem that I meet in LuCI WebUI, but there is some:
QOS - In Tomato I have default 10 profiles of network traffic type. I can set guaranteed bandwidth for each type. In OpenWRT I didn't find anything like that. Default QOS settings are rather simple. And bandwidth seems to be possible to set just globally for WAN. In general - QOS in OpenWRT seems to be very simple and looks it has much less options than Tomato.
Scripts - that's second big difference. In Tomato I have fields to run additional commands for almost every event: USB mount, dismount, WAN restart, connect, disconnect, boot etc. Plus additionally crontab. All in web interface. In LuCI I found only startup, and crontab. But If I wish to run the command on WAN restart, or Firewall reload - It can't be set.
WebServer with PHP and MySQL - In tomato I just tick option and have fullfeatured Ngnix + PHP7.2 + mysql that basically works. In OpenWRT I know that I can install uhttpd module and it can be managed by LuCI. There is also MariaDB and PHP packages possible to install, but they seems to be not linked to uhttpd at all - no any luci module for them at all.
I would list more, but have no time for that, and these are most annoying me - with better QOS, better Scripts and Web server I would be happy.
In this moment, I want to say that I'm not afraid to use console. I have almost 20 years of linux experience, so I remember times when it was impossible to even install linux without knowledge of console commands. For me it is just question of time. WebUI if is well-organised can really save time. Reading documentation, managing files and options in console to set up QOS or web server while it could be as simple as in Tomato seems to be big waste of time.
So my answer for question: Can OpenWRT substitute FreshTomato? is NO.
If you wan't, you may try change my mind showing me that I'm wrong.
Some chipsets might not work as well ... the R7000 for example. I understand Tomato has access to their closed-source drivers whereas OW does not. You should check the OW wiki to verify what works on that specific hardware prior to switching.
Even in the GUI, OpenWrt is geared more toward the administrator having total control of the OS at a lower level rather than choosing from canned operating mode scenarios.
EA6900 is not a good candidate for OpenWrt since it uses a Broadcom chipset.
I think you didn't understand me. I didn't ask if I can install OpenWRT on EA6900 instead of Tomato. I asked If OpenWRT will work for ma as good as Tomato does? As I tested so far, I'm not happy with OpenWRT, As I said. I don't see proper QOS, Everything is like ... Ikea furnitures - you have to put everything together by your own praying you will get what you want. It would make sense if installed modules would give you more possibilities, but as I said they don't. Tomato out of box gives user much more features and options. And sure, I understand that everything can be done in command line.
But the thing is that in Tomato you can do command line scripts as well. You can install Entware and use most of OpenWRT packages anyway. I'm not saying OpenWRT is bad. It seems to be not for me. Maybe I would need more than 20-30 hours.
I'm just disappointed. I feel I wasted the time.
OpenWrt is geared more towards SQM these days and there's a package called luci-app-commands that you might like, but yes, they'll both take a little digging and experimentation to get them to your liking, mounting/unmounting can be done with the click of a button in most cases after installing a few packages.
You count your time, but easily spend time of people, answering you. Generally speaking, we are absolutely indifferent, what do you feel, and our task is not to persuade you to use OpenWRT. Use Tomato and go to forums, dedicated to Tomato, and stop writing here.