It is worth trying a few. Sometimes you think you may like a sound at the start but after a while it becomes annoying. Find a sound that relaxes you. For those apps that have a cost, I would suggest just downloading the free versions first to see what different sounds they have before purchasing.
Below is a list of apps clients have said they have found useful. Some are to help mask tinnitus, some are for relaxation and mindfulness:-
Sleep Pillow by Fitness22 Ltd (Free/£2.99)
SleepBug by Arnt-Henning Moberg (Free/£1.99)
White Noise (Free) by TMSOFT.
Headspace: Guided Meditation and Mindfulness (Free)
Smiling Minds by Smiling Minds (Free)
If you have any others that you have found useful please let me know and I’ll add it to the list.