It really depends on the type of functionality that you're actually looking for and the distro - desktop environment that you're using.
By functionality I mean: it resumes to two scenarios:
1.- You want to be able to open apps but switch to the app if it is already open.
2.- You want to always open new instance of the app, if you have chrome already open it will launch another instance of the app in another window.
For the second scenario there are a bunch and almost any app that is listed on your link will do the job, however the first scenario is the tricky one and IMO the most useful.
For scenario 1 recommend kupfer and it works very well in different desktop environments (Gnome and Xfce tested)
In terminal:
sudo apt-get install kupfer
then launch it
kupfer
With ctrl + space you launch it, then type your search and voila!
However there are some apps that doesn't adhere to scenario 1 no matter the launcher.
Note: The Gnome default search app (the one triggered by windows key) works the scenario 1, however it does not work with websites.
Hope it helps!