Armand
Google
A unique, hilly park cut through by the RER B train line you can peek down into. A product of the start of the 20th century, there are several posters under the railway bridge in the north end describing its history.
A great place for kids. There are many play areas, swings, things to climb on etc. For me the highlight was the large mountain-shaped car track (pictured) I used to spend hours on as a kid.
The park has a very interesting aesthetic, with many winding, naturalistic paths with concrete handrails that looks like wooden branches. Great for a little wander through nature.
The only real downside of this park is that, because it's so hilly, it's not possible to get around in a wheelchair without someone strong to push you. I haven't checked if all areas are reachable without going up stairs, but I generally wouldn't recommend this one to wheelchair users in general.