We have bought many different treat dispensing toys for Miki. I highly recommend the Kong toys; they are pretty durable and pet stores usually have a good selection of them.
Here are some examples how you can use treat dispensing toys with your dog and how much time it approximately took Miki to empty the treats from them. I will also tell you what type of treats I feel are the most suitable for each toy. However these are the treats Miki likes, but I hope this can give you some ideas.
You can read the whole review by clicking on the thumbnails.

Trixie Snack Spinner
I’m sorry to say but Trixie Snack Spinner is quite a flop.

Trixie Roly Poly
Trixie’s Roly Poly is quite good compared to other treat dispenser toys.

Toys combined
You can join some food dispensing toys together to make the toys more difficult.

Space Ball Stellaron
This Space Ball Stellaron toy is actually meant for fetching, but we have used it as a treat dispenser.

PetProjekt Tretbal
PetProjekt Tretbal is an ultra durable rubber toy that is almost impossible to break.

PetProjekt Holobal
PetProjekt’s toys are usually very smart and clever and this Holobal is no exception.

Northmate Green
In addition to normal food bowl, we have this slow feeding bowl that mimics grass, and this one is the larger one of the two available sizes.

Kong Wobbler
Kong Wobbler is very durable toy and you can easily make the toy more challenging.

Kong Traxx Extreme
Kong Traxx Extreme is the most durable toy we have ever bought to Miki.

Kong Satellite
Kong Satellite has been one of the most difficult toys we have bought for Miki.

Kong Quest Wishbone
Kong Quest Wishbone is very durable toy but it doesn’t give much of a challenge.

Kong Quest Star Pod
Kong Quest Star Pod is a durable toy and it’s a good toy if you can find right size treats for it.

Kong Gyro
Kong Gyro is a bit different food dispenser ball because it has a ring attached to it. The ball rolls around its axis making the toy a bit more challenging.

Kong Genius Mike
Kong Genius Mike is a durable and versatile toy.

Kong Genius Leo
Kong Genius Leo is one of Miki’s favourite toys.

Kong Classic (Extreme)
This Kong toy is extremely durable and it’s an absolute classic.

Karlie Boomer treat ball
A treat ball is a must in every dog’s toy selection.

JW Playbites Caterpillar
JW Playbites Caterpillar toy is my new favourite, because it gives Miki a long-lasting challenge.

Interactive games
You can find all sorts of interactive games from pet stores, but it’s wise to consider if your dog actually needs one.

Busy Buddy Twist'n Treat
Busy Buddy Twist’n Treat is one of my favourite toys because it’s so durable.

Busy Buddy Magic Mushroom
Busy Buddy Magic Mushroom is a very challenging treat dispenser toy although the difficulty is adjustable.

Buster Food Cube
Buster Food Cube’s idea is great because a cube won’t roll by itself on the floor but needs to be pushed all the time.