Do I upgrade my iPhone 4 to iPhone 5 or HTC One?

I hope you can give me some advice on which smartphone to upgrade to.

I currently have an iPhone 4 and I'm due for an upgrade. I have heard a lot about the HTC One; After looking at the reviews of this phone, I must admit that The HTC One looks fantastic.

However… The reasons that I'm dubious about switching to a HTC One are…

1. I have had my iPhone 4 between 2-3 years and over the time I have purchased at least £500 worth of music on 'iTunes'. (Will I lose this music or can I transfer it on to a hard drive and convert the files on to the HTC One?

2. I also have an iPad and when I download certain apps, I like to put them on both my iPad and iPhone. Would I have to download both the Android app and iTunes app in order to do this?

3. I think the iPhone is amazing. Do I take the chance of upgrading to a HTC One when I already feel like I have the perfect phone?

I hope that all makes sense, any advice would be appreciated.

Also, if you can compare the two different phones and what phone you would choose based on my questions then that would also help.

Ok HTC One is the best phone released in the 2012-2013 all agree its better than the S4 and than the iphone 5, you want differences here they are:
1-Cpu 1.7 krait quad core (htc one) vs 1.2 cortex A9 dual core
2-5.0 super lcd 3 (htc one) vs led backlit ips iphone 5
3-Android 4.2 vs iOS 6…
And the htc one has beats audio

Ok now the other questions, I don't believe you can do what you want to do with the music but you can download music from any website for free and transfer it to the htc one since it can be done because its not like the iphone/ipad/ipod
And yes you would have to download the app in both android and apple to have them both in the mobile and the ipad
And last question, yes you should take the risk its worth it but if you really like your iPhone and don't have any issues you can keep it since the most important thing is to be satisfied

I advice you to try the htc one and apple iPhone 5 before any decision to know if the android OS is going to be hard for you to get used to, but android is great and htc one too
Hope this helped