I agree with shep, you are just in the throws of buying and the mowing season is about over, you are under no pressure to have kit immediately...although believe me it will soon come round ! You don't need 5 mowers.
You could value all the equipment by looking at 'completed listings' on ebay to see what they make. Then do your sums, buy it all and resell what you don't want if you can be bothered.
I have quickly google imaged all the kit, id say the husqvana outfront and all the john deere kit are worth having, forget the rest. That said the JD ride on mower and the husqvana will do the same job....so id choose just one.
It hard to advice people what they are going to need without seeing the property and knowing their skills and aspirations. But I can tell you how I manage my grassed areas.
I have 10 acres in total- most is agricultural grass land which I let others graze with sheep or hay time, but we have an acre of wood, and probably another 0.5 acre of veg/potatoe growing where I mow around the growing beds. And about 0.5 acre of other areas--orchard drive sides that I manage with mowers and then the lawns associated with the house.
I have a ride on mower similar to the John Deere you list. I use this to mow the lawns, the awkward bits of the orchard, the pedestrian routes through the wood and the drive sides....id say somewhere around 0.5 acres in total.....I can do the lot in an hour and a half on a good day probably more realistically 2 hours...I only pick up the grass on the lawn around the house. I have a trailer a bit like the cart mentioned which fits on the back of the ride on...it is really useful for carting away lawn arisings, but also for all sorts of other little carting jobs around the place...eg. if the missus is weeding boarders...or clearing out the poly tunnel etc etc.
I then have a proper tractor...a massey ferguson 135....believe it or not you can probably buy a good second hand one of these for similar money as a decent ride on mower , it will out last any of them...and probably you. For the back of it I have a finishing mower (this is like a topper but gives a better finish ie close to lawn standard) they are a bit dearer than a topper, but worth it as you can use them as a topper too. With this I can cut all the rest ie round the growing beds, the orchard, the main tracks through the wood probably getting on for an acre in total in about 0.5 hour. This machine is completely on top of its game not stressed runs on red diesel and uses hardly any. Parts are dirt cheap, any agri engineer can service and fix them for you. I use it on the lawns too if the grass has got too high on me and the ride on is struggling.
I then have various attachments for the back of the 135...a simple transport scoop which is great for all sorts of tasks, from moving heavy objects, taking the bin down to the road, scooping gravel from the heap to fill pot holes in, shifting garden waste ..the list goes on and on. I have a larger tipping trailer for it, great if you've been pruning trees and you have bulky stuff to move to a bonfire or compost heap, a plough and rotavator the list goes on.
I have a walk behind too, but to be honest I haven't used it this season, its hand for awkward bits you cant get at with the ride on....but I have more or less eliminated all of them.
Tip...when planting trees make sure they are far enough from the fence or other obsticles so your ride on will go between them !
Anyway that's my experience I hope it is of some help. I read your other post and was inspired to give you some help in this one. I have been on my place for about 8 years and every day is a school day...despite growing up on a small holding and working on an adjacent farm as a teenager I have made mistake after mistake. But it is my hobby and my pleasure (not my living) and I love it. Perhaps by retirement it may give me a job that supplements my pension is my greatest hope. I hope you enjoy your journey. And keep posting here , lots of good advice and experiences to be listened to by regular posters.