I work out in my small flat so all of my equipment is optimized to be used and stored in my bedroom. If I had a whole garage, I'd make a few additions.
What I have:
1) Interlocking floor mats to protect my joints, the floor, and keep the neighbors from complaining about the noise when I do cardio
2) Yoga mat
3) Yoga towel (doubles as travel mat)
4) 2kg and 4kg dumbbells
5) 2x 20kg adjustable dumbbell sets (I could really get rid of the separate 2and 4kg sets, as I can make weights ranging from 1.5kg to 10 kg with these sets)
6) set of tubing and resistance bands (mostly I have these because they travel well, I don't use them at home very often)
7) Lebert Equalizer (by far the most expensive item but I don't have any doorways in my flat that would hold a pull up bar. The Equalizer has other uses, but I'd have preferred a pull up bar.)
8) foam roller
9) stability ball that doubles as my desk chair
All of this was accumulated over about 6 years and looking for used equipment and sales. In my dream home gym, with plenty of space and high ceilings, I'd add a jump rope, pull up bar, bench, set of medicine balls, a BOSU, and mirrors to check my form.