Depending where in the world you live, there are other frequency bands available.
In the US, you can use 1.3GHz - if you have a radio ham licence. This has much better propagation than (Distance) than 5.8GHz, even if the aerials are a bit bigger.
In the UK, things are more limited, so you are stuck legally with 25mW on 5.8GHz. Frankly this is a challenge with analogue systems, so many people (ahem!) use a slightly more powerful TX to give them a usable range.
The 2.4GHz band is very congested, with everything from microwave ovens to wifi, to video links and wireless video and audio senders all competing for bandwidth. Some of these devices can "wideband" their signal over quite a lot of the spectrum, making things even worse.
Nothing wrong with the Walkera system and even with a 2D gimbal, you can still get really good images. Check out the flight time though, as I understand it can be quite limited. Trade support is not quite so good, so you may struggle to find some accessories and add ons, but it is still a very decent rig.