Happy to help @JihadAqel and you are correct, the advantage with external antennas is that you have much more flexibility with respect to where you want to "point" the RF energy. It's not changing the signal strength, that is, a semi-directional or directional antenna like the wide and narrow patch options only provide passive gain by focusing the RF energy to something less than omnidirectional.
When you say "coverage and signal strength" you might also be thinking about distance from the AP, and there is no single correct answer. That's always an "it depends" answer, and why you generally never see distance specs on any data sheets.
The critical figure or merit there is Signal to Noise ratio, which will be a multi-variable moving target with multiple dependencies involving lots of things from building materials to the type of client device to user density, etc. So there's no way to say (on a data sheet) that you would have a specific signal strength at a certain distance that corresponds to a given MCS rate. The signal strength and coverage for any given client's data rate can vary significantly over time, even in a relatively status quo environment. This is also where the recommendation of "do a site survey" usually comes up, especially if we're talking about more than a handful of APs. A proper site survey will give you a great idea of AP density and antenna type and placement.
Also, side note to remember that you also now have RF Profiles in Dashboard, so it's simple to set up (for example, in a K12 environment) different profiles for classrooms versus auditoriums versus outdoor sports fields, and have the RF settings automatically apply to all APs according to their profile. So regardless of your deployment scenario, you might consider (if appropriate) leveraging RF Profiles for any "E" access points separately from regular non-E APs.
