Multiple access points VS new wifi router OR mesh network

So, some help and suggestions please regarding the above subject! :D Currently we have:

- Fortigate Router + ONT + Switch- Synology NAS DS1515+- Plex Server (SFF PC)- Apple TV (3rd gen, hard wired)- Airport Express (little white puck, hard wired)- Airport Extreme (tall white puck, hard wired)- Philips Hue bridge- Devices: 2017 MacBook Pro, 2018 Surface Pro, iPhone 6S+XS, iPad Pro

We have a two story house with mostly garage and office/spare bedrooms etc downstairs - then main living/kitchen/dining, small reading room + main bedroom upstairs with an outside area off to the side of the house. At the moment i have all the tech bits in a small wall mounted server cabinet in the garage, the Airport Express behind the TV (central to the main living area, kitchen, dining and front deck), the Airport Extreme in the small reading room, coving bedroom, downstairs (to a degree) and outdoor area.

Main Problem: The Airport Express is just getting too slow and i would like to replace with something much faster as we often do work on our dining table (the office desk is hard wired) and its just not cutting the mustard with the new(er) laptops. I must admit I like how the two apple access points just work as one network, nice and simple. Basically need faster WIFI!

I have been thinking of these options and wondering if someone can assist with suggestions or options?... My thoughts up to now:

1). Replace the Fortigate router and wifi acesss points with a Synology RT2600ac, position this behind the TV which is central to our entire house basically. I am very comfortable with the Synology eco system but is the Synology best option in this case and would i need an extender of somekind to get out to the outdoor area.

2). Swap the Airport Express with an Airport Extreme around? The only issue is that laptops seem to flick to one or the other when working at our dining table alot.

3). Replace the Airport Express with an Airport Extreme - but i just seems like apple is leaving this behind.

4). Replace the access points with a Wifi Mesh Network. Is this needed if you have the areas where you are putting the devices hard wired?

5). Other?

Any help is very much appreciated.

Thanks

Simon