I need to replace a small fleet of older ar9331-based travel routers because they only have 8MB of onboard storage, so I was looking for something similar with at least 16MB of storage, a USB2 port, and 2x ethernet ports. I use these in client-mode as serial console servers rather than actual routers.
The GL.iNet GL-AR150 and GL.iNET GL-MT300N-V2 are good fits, so I decided to compare the two.
I remember looking at the yellow/mango GL.iNET GL-MT300N-V2 a couple of years ago and was not impressed. OpenWRT didn't officially support it until 2018, and the MT7628 wifi was known to be unstable and bad. But I gave it another try anyway. Fortunately it looks like most of these reliability issues are no longer a problem.
The white GL.iNet GL-AR150 has the same old super common ar9331 SoC, so it's characteristics are well known. Unfortunately, the ar9331 has an interesting bug where the USB and wifi share a clock source. IF the wifi is scanning frequencies, AND you have a USB1 device in-use, the USB port will often break and need to be reset, which is exactly what happens to me when using serial USB adapters. I usually work around it by using a USB2 hub in between.
Both devices have the same 3x LEDs, a switch, a reset button, 2.4Ghz 802.11, 2x 10/100 ethernet ports, 1 USB2 port (with GPIO on/off control), 16MB NOR flash, and use the same size chassis/boards. The GL-MT300N-V2 has the advantage of 128MB of RAM compared to the 64MB on the GL-AR150. The GL-MT300N-V2 also has a higher Mhz rated CPU, so theoretically it should be faster.
I ran a few tests with openssl and gzip to test those CPU differences and overall I'd say the mt76 CPU is 50-90% faster than the ar9331. For example a 20MB file compressed with gzip took 69 seconds on the GL-AR150, but only 40 seconds on the GL-MT300N-V2.
One downside of the GL-MT300N-V2 is that it gets much warmer than the GL-AR150; like 10C hotter at idle. It's obviously using much more USB input power. I even found that it had problems booting on one of my shitty chinese USB hubs where the GL-AR150 worked fine, because the hub wasn't putting out enough current. I blame the hub more than the router, but the problem made the power requirements apparent.
The GL-AR150 costs $2-5 USD more than the GL-MT300N-V2. Either Mediatek is giving GL.iNet a better deal on their SoCs or the historic use of the lesser-supported mt76 warranted a lower price.
Something I did not benchmark or compare with these devices was network performance beyond reliability. It's just not important to the way I use these devices. I did check iperf over the 802.11 wifi and the GL-MT300N-V2 unsurprisingly gets much better bandwidth, double overall. Note that both devices had a similar range and reliability. For most of my tests at a typical one-side-of-the-house-to-the-other distance I was doing about 15Mbps on the GL-AR150 and 30Mbps on the GL-MT300N-V2, though I did see far far more retransmits on the GL-MT300N-V2's connection. Such is the price of speed.
One strange attribute of the GL-MT300N-V2, which could be important, is that it only has a single real ethernet interface, eth0, whereas the GL-AR150 and other ar9331 devices have two, eth0 and eth1. To get the two ethernet jacks, the built-in switch is used and so the GL-MT300N-V2 has an eth0.1 and eth0.2 for it's LAN and WAN interfaces. This also means that swconfig use is mandatory, whereas it's optional on ar9331 devices like this.
Overall the GL-MT300N-V2 has come far enough along to replace my fleet so I'm probably going to go with those instead of the GL-AR150. It will fix that annoying USB port bug I sometimes run into, it will be a few dollars cheaper, I'll get double the RAM, and more performance.