I've had multiple plushes around me and grown attached to over the years, so there's not really a set one I rely on when I need a hug. My most recent one I became attached to is a Mr. Mew plush I got as a gift. It's big enough to hug and small enough to act as a normal decoration among my collectables. I really like having it around me. Even just looking at it makes me feel at ease.
As for my oldest one, it's a small pink puppy with a TY tag. I got it from a kind lady during Halloween when I was 4 and it's been with me ever since. Now, I keep it in a special box alongside other sentimental things from my younger years. Love that thing to death. Plushies are great.