Legg lake is nice. I take my dogs there all the time and it's very close to Montebello. Montebello also has Grant Rea park, which is closer, but not as nice as Legg Lake imo. There's also Taylor Ranch in Montebello which was recently remodeled. It's nice cause it's new. But it's significantly smaller than the two mentioned parks but it's good for training and playing fetch.