Does RAM brand actually matter, or should I just buy the better specs?

Brand matters, just not necessarily because of the name on the heat spreader. The company selling the kit may not make the memory chips, but it still chooses the components, assembles and tests the modules, and handles warranty support.

I'd compare the warranty and return options alongside the specs. A cheaper or faster kit isn't much comfort if getting a faulty one replaced is a hassle.

Check the exact kit's part number against your motherboard's memory compatibility list, often called the QVL. A listing means that specific combination was tested. Not being listed doesn't automatically mean it won't work.

Also check that the kit has an appropriate XMP or EXPO profile for your system if you want to run its advertised settings. The CPU, motherboard and firmware can all affect whether those settings run reliably.

CL30 is better than CL36 when the kits run at the same transfer rate, but the real performance difference depends on the workload. Capacity and speed matter too, so don't compare the CL number by itself.

If everything else is comparable and the prices are equal, CL30 is a reasonable preference. I wouldn't pay a huge premium for it without checking whether your applications benefit.

For a normal build where you're just enabling XMP or EXPO, I'd pick a kit with the capacity and speed you need from a seller with a decent return policy. Don't worry too much about tracking down a particular chip manufacturer unless you're interested in memory tuning.