Here's my Home Gym I put together about 4 or so months ago.
Only used it for 2 or 3 weeks then got some serious food poisoning for a week, then got busy at work, etc, etc, and haven't trained since.
Anyway, putting it back to use again now, hopefully for the long run.
Some details:
The 2 red items, Chest support isolateral row and T-Bar row are old, from my previous set up, so I left them in there.
The Smith machine is old too.
I'll use it on some exercises so I left it in there too, I like doing incline bench press and standing calf raise on it, maybe will do some other variations on it.
The seated calf raise is old too.
A few standard size bars - curl bar, triceps bar.
Everything else I brought in fresh:
22 rubber mats 1m x 1m (so my gym takes up 22sqm of my garage)
Power rack with high/low pulley attachment + dip attachment
Flat bench
FID adjustable bench + leg attachment + preacher attachment
2 x olympic barbells
Trap bar
Dumbbell rack + 4 pair of dumbbells (don't use these much at all currently)
Bumper plates - 20kg x 2, 15kg x 2, 10kg x 2
Metal Oly plates - 20kg x 2, 10kg x 4, 5kg x 4, 2.5kg x 4, 1.25kg x 4
Rubber standard plates - Some 5kg's, 2.5kg's and 1.25kg's
It may sound silly, but to be honest, the best thing in my gym is the rubber flooring.
I started with a blank canvass and as soon as I laid that stuff down, it just felt right.
Feels great on bare feet and you can drop metal weights on it without having to be delicate.
When I tried to train in my garage gym previously I only had one rubber mat about 1.5m x 1m and the rest was just plain concrete.
Always felt dusty diry and cold and changed the mood in a bad way.
Now, it feels great.
The floor is the largest area you see, so when it's clean and uniform, everything feels more organised (my personal views).
The obvious essentials out of all this equipment that I use is:
Power rack
Flat and FID bench
Barbells
Olympic plates (I mostly use the plain metal plates and sometimes bumpers, depending on exercise)
Dip attachment for power rack
Mirrors - These are actually from my old set up, bought from eBay (2nd hand sliding wardrobe doors)
Some hardcore guys don't want mirrors in their gym.
I love them and think they are a great tool to check form on certain exercises.
I do use some other attachments and equipment for generally smaller exercises (not compounds), but they would not be essential.
Good for some variety though, which is what I need to stay motivated.