I try to avoid them. I love domain forwarding and use it as much as possible. But of course, you need to buy it.But google shortener looks more friendly than bit.ly
Some people still don't have an idea about URL shorteners and think that they are some spammy links. That's why I think google looks more friendly
I use TinyURL because you have the option of providing your own name. If you can somehow use a name that makes sense to the person reading the URL it helps with continuity in branding and helps you to track which shortened URL is for what product.