DECATHLON's fitness brand offers useful suggestions for your practice.
Choosing an abs exerciser depends on your goals: working your deep muscles for a flat-tummy effect or superficial muscles (hello washboard stomach!). There are two types of exercisers that you can use to work statically or dynamically.
For Superficial Ab Muscles
If you want to work your abs and create a ‘washboard’ stomach, you'll have to exercise all your superficial ab muscles. To do this, you need to work dynamically (that means lifting the chest) with abs exercisers like crunch trainers or ab benches that let you do various exercises. You should also consider how durable your pick is, how many functions it has (do you need many?) and how compact it is.
For Deep Core Muscles
To slim down or work towards a flatter tummy, you’ll need to work on your deep core muscles through static exercises. In addition to aesthetics, this type of exercise helps improve posture and protects the lower back. Try a gym ball which will create instability that will make your core muscles work hard to counter. Remember : weights benches won't let you do static strength work.