The Sonyxerpia z series looks good but had some problems with Sony before I would go withHTC but I don't like the camera on the phones my budget is around£200
The oneplus one (as long as you don't mind 3g only on giffgaff) and moto g are well recommended phones in their price brackets.
When I want to buy a product, especially in such a wide environment... I always go on
This is a website where professionals try electronic things, compare them, say what's good and what isn't good about them...
I followed their advice and bought a LG G3, which was said to be the best at the time... and to me, also a good deal...
I wasn't sure about buying LG, as none of my friends had had good experience with their older phones...
Well... I'm happy I followed the professional's advice as I looooove my LG G3
So check the website, look for what you're looking for (it might not be "the best" from them, check the positive and negative points about each of them... it's quite detailed but you also have a summary for the tests...)
Hope it helps you !
@cliffy88 think you will see from all the posts here there is no short answer, all depends on needs and budget, but like a few on here i can personally recommend the 2nd gen MotoG. I always used big name ie Samsung etc phones, but recently used older models as they were cheaper, and found that the latest models were full of gimmicks to justify the high price and the older phones were just too slow, but i got my son A Moto G last year and although a fantastic phone, it was let down by measly storage and no SD card slot, but the 2nd gen has an SD slot, so got myself one and at £140 it is equivalent to about £5 per month on a 2 yr contract then add to that a giff gaff sim and you have a really nippy phone with a fantastic screen, and uncluttered vanilla android, without all the gimmicks and bloatware of the big companies flagship models, at under £20 a month, so as I said it depends on your needs and budget, but all I can add is that the motoG has given me the best android experience with the best value for money yet
edit to add. I almost forgot to add that an unexpected bonus for me was the battery, initially I was put off by the fact that the battery couldn't be removed as I have always purchased a spare battery, and use it a lot as I work 12 hour shifts, and my battery never lasted the full day, but for the first time ever I have not had to tailor syncing etc to preserve battery life, and the moto G easily lasts a full day, I also noticed a post mentioning no 4G, but that was the 1st gen, 2nd gen supports 4G