Switching vendors advice

Hello, I need some advice regarding switching brands. I'm currently working doing and internship on a small to medium sized company. It is actually more medium sized, but my work concerns only the HQ, with 200-300 employees out of the ~1800 employees they have. I'm currently working on a project of overhauling the building network. To make a long story short, it's the kind of business that grew a bit faster than they expected in the past few years, and there's an IT department with no networking expert (or even someone that know something network-related) working there. Seriously, they barely manage their equipments. As a result, the net has grown to satisfy the current needs, it hasn't been a planned growth. So i got here and it's a bit of a mess, no documentation, lots of bottlenecks, lots of design decisions that make no sense. We have a fortigate, one cisco L3 switch (old) that for some reason has routing activated but has all vlan interfaces shutdown (?), 3 cisco 2960's, a couple Dlink and lots and lots of useless tp link switches (seriously useless and really old). No wonder everyone complains about internet and servers access.

So anyway, my current aim is to provide my boss with a list of possible switches we can buy to replace nearly everything in the current network. I've been looking at an endless list of vendors, models, and I decided that I want two things: 1) The equipment must be as modern as we can buy it: The staff grows approximately 20% to 30% each year, so we can't afford to buy some olders models just because it's a lot cheaper if that means we should be looking for a replacement for whatever reason in a year or two. 2) I want a single vendor environment (or maximum 2 vendors): with the exception of the fortinet FW of course, I don't see fortiswitch models as a viable solution; running multiple vendors is not actually a problem, the problem comes when your multiple vendors are cheap pieces of garbage. I prefer to have access routing since there's a lot of different servers running for the staff to use, a lot of interdepartmental file sharing, etc.

So i've narrowed it down to 3 options: Cisco (of course) since my bosses are big cisco fans (and yet they haven't replaced those cheap 15 years old tp links smh), 9300 series for the access layer and 9500 series for the distribution layer. Hpe aruba, 2930f (JL260A) for access and 3810m (JL071A) for distribution. And finally , mikrotik as a cheap solution, model CRS354-48G for the access and I haven't chosen a model for distribution. I'm currently contacting official vendors from each (except mikrotik since it's so cheap, I've put that one on a side) to get pricings and discuss it with my boss. However, I'm afraid they will go with the cheapest solution (I've never worked with mikrotik) just because it's cheap, when they are perfectly capable of spending a decent amount of money in any of the other two (I'm not guessing here, trust me). In that worst-case scenario, how much of a good or bad choice is mikrotik (and specially that model)? Am I overdoing it with the models I've picked? Is there any other intermediate option I should be considering?