Depends on what you want in a buddy. Dogs are the obvious buddy choice since every dog actually wants to be your friend. I have a very dog-like cat who is very affectionate and follows along on walks etc but it's hardly the norm.

But I do want to mention reptiles, especially crested geckos, as being a surprisingly practical pet and while you aren't going to cuddle with them much they give you a lot of attention during feeding and are very calming to be around and watch while they roam around their terrarium. Sadly many lose interest fast but that means craigslist and similar websites are crawling with them so you can get a terrarium and gecko pretty cheap and if you live where the indoor climate is steady taking care of them is very easy and lower maintenance that both an indoor cat or a dog.