I'm surprised this hasn't been mentioned yet, but a fuel tank and pump in my shop. At 72, I'm awfully tired of wrestling 5 gallon cans for 4 machines...Dan.
Regardless of your tractor uses, a storage shed and fuel tank with electric pump is the most universal thing and the most appreciated that you can get. I would build a shed, make sure the doors are high enough to park your tractor inside without lowering the ROPS. I would do this prior to getting the tractor, then put a fuel storage depot in it so you are ready to go when the tractor is delivered. Dont ever let your tractor set outside in the weather.
Much of the "implements " that you need depends on what you plan to use it for. Personally I have no use for forks or a grapple now. When I first got my place a grapple would have been nice to pick up the brush but that use is all gone except for the occasionally storm damaged tree limb that falls and that is handled quicker than I could put on a grapple by just sawing it into small pieces and loading in the FEL.
If you plan to do a lot of grading with a box blade or grader blade, TOP N TILT would be handy but I dont do that so none for me.
I got a bush hog as my first implement and used it a lot, now maybe once a year for 3 hours is all I need it.
I also bought a disk harrow that has been replaced with a tiller that I also only use once a year for the garden and I may not even use it this year due to deer eating
up everything I plant so likely I will put in bedding pots this year.
I also bought a landscape rake that has pretty much become just a place for the chickens to set on. I do all my road maintenance with the FEL by back dragging.
I suspect that lots of folks buy things they use for a bit then find something else that works better.
As I said, your implements depend on what your usage is and only you can determine that. MY go to is my Kubota B26 TLB. I would not be without the backhoe. Just used it today to bury a cow for my brother in law. Your usage likely will vary, but I wont be without my TLB. I got it shortly after I bought my LS and it has over 600 hours on it. My LS has only 160 hours and I only use it to bushhog, till my garden and occasionally haul some dirt when I need more that a yard or two. Small quantities I use the Kubota TLB.
I am glad I have the cabbed LS tractor with heat and air but it just doesn't get used that much due to it's larger size, the B26 is just so much easier to work with.
So choose your tractor size accordingly, weight and HP is nice but too big is just as bad as too small.