Oh, I'm flattered but just a keen amateur
What with work and a new home I'm setting up, I wouldn't have the time to do it directly, sorry.
I think there is a continuum of capability vs ease of use and you have to kinda choose where you sit. The apps you speak about are all quite capable and easy to use. But they all have limitations around variables for example, and range of devices supported. You end up using IFTTT to cover your devices. I would recommend you choose the one that has the best coverage of your devices natively. With Sequematic, there are no native integrations so you use IFTTT for everything while the system runs the simple logic. That's also fine. It just means you have that latency of IFTTT all the time and a lot of messing around with webhooks.
Like quite a few others on here I decided to go for Hubitat. It's a hardware hub which tries to run as much as possible locally, which means the performance is fast. It also means it's not going anywhere. The company can go bust but you will still have the hub and most of its capability. However, again, not all my devices are covered and its necessary to use IFTTT for some things. There are a bunch of community integrations but they are not officially supported and can mess up or slow down the hub. And because it's local it's more problematic to support remotely. You can kinda view it as a shrink-wrapped rPi type of device. But there's a very active and helpful community. I like it. But it's definitely for the part-time tinkerer, in my opinion.
Then there's the rPi route running something like Home Assistant. A bit tricky to set up but incredibly flexible. An extremely active and large community. But get ready for a world of pain unless you are a real techi. I'm also playing with this approach but it's not easy at all in my opinion.
At the other end of the spectrum, it's pretty incredible really that Alexa and Google Assistant, for all their thousands of supported devices, can't string a few steps and some simple logic together. They have routines that do very little and really no logic capability whatsoever. It's pathetic and time it got fixed. While they cater to the masses, they provide next to no useful logic capability and so we are left working with frankly 2-bit companies or start-ups that have no sustainable business model to do what is really the simplest of things.
You have to choose your route, balancing degree of pain/time against flexibility/control. Good luck!