I used to work for a large mobile phone shop and we sold our own insurance. It really depends what you need; some will cover for all scenarios and pay out regardless but is expensive (up to £13.99 a month!) and others are a bit hit and miss. Generally, the larger companies are better (Protect your bubble for example) however make sure you understand the policy. Some wont cover for water damage if it gets wet in a pocket due to rain or moisture as this is seen as negligent use of your phone whereas some wont care. If you say you ‘accidentally’ spilt water on it, different ball game (not promoting fraud)
I sold several insurance policies on the back of ‘my bank refused my claim for this or that’ as the all in one policies are generally a bit naff and cover for few scenarios.
You also have to weigh up do I need this. Are you a clumsy person? Do you break your phone regularly? Could you take cheaper steps to prevent damage/loss/theft? (decent case, not taking it with you, even moving which pocket you keep it in) How much is my phone now worth? If you are paying £8 a month over a year period, you crack your screen, make a claim (£40 excess) thats £136 that you could have saved. Most places will charge £50-100 for a screen replacement for most popular phones.
There is also the case of how much you rely on your phone. Is it a live on work on cant be without it or just an occasional thing? Insurance may be better in that good policies will swap old for new quickly or even offer warranty swaps within 24hrs instead of it taking up to a month to repair.