Looking for bike recommendations

[Rosebud2005]

Hi, what’s the favourite bike choices these days? Dh got one from a cycle to work thing about three years ago to get him fit and to help ds who developed a bit of a fear of his bike after a bad fall when he was 8... he’s 14 now and it’s been in the shed ever since and is a really expensive one. He then said ds can have it - not a chance! My friend’s son was mugged for his bike last year. So while he is showing an interest in cycling again and I want to get him a good bike I don’t want him having one at nearly £1000 lol

My 12 year old has just got a Cube, its really good and he loves it, it was £450.

Isn't he better to use the one you have if it's just lying around and get bike insurance?
If not go to an independent dealer rather than a multi.

It’s not that I don’t want him to have a decent one but where we are there have been too many bike thefts and as I said my friends son had his stolen off him too. I wouldn’t want to put him in too much of temptations way

I suppose it depends on what the old bike is, and what you were proposing to replace it with. And also what kind of bike thieves you are potentially dealing with if that makes sense? Organised bike thieves tend to go for newish, high end bikes. A sub £1000 bike bought 3 years ago is unlikely to be of much more interest to the "serious" bike thief than something costing half the amount new now. Like cars, bikes depreciate very quickly when they are first bought so the old one may well be worth less than whatever you would be thinking of buying new now.
Opportunist bike thieves will just take whatever is easiest for them, so that's always going to be a risk unfortunately. Lockdown has led to a shortage of bikes so some unscrupulous people will be out to steal anything I am afraid. All you can do is impress upon your son the importance of being careful and buy him a decent lock. You might not need specific bike insurance - check your household contents policy as many include bike cover up to a certain value.
Kids stealing other kids bikes will probably be more interested in how cool they perceive the bike to be rather than what it cost. So if you opt for whatever is popular with teens in your area, that might be seen as far more desirable than your husband's old bike and so be a higher theft risk. "Dad's old bike" might be very uncool! I'd look on ebay, Facebook marketplace etc to get an idea of what bikes of a similar age and type as the old one are going for. That will give you a rough idea of the desirability. If they are going for a couple of hundred quid you may as well let your DS ride it. And if they are selling well you could always sell yours to fund the new one - its worth nothing to you (and is at risk of theft) sitting unused in the shed after all.