Lots of suggestions there for you Bethyboo! It also depends on your personal preferences. I love some of the tank style set ups, but I much prefer having a cage - the ventilation is so good, you can attach a roof run to the bars, and attach shelves and hang things, plus front opening doors are good to get access and interaction with your hammy. Which has just reminded me of another cage! The Borneo L (Cypher has this) - which is available on German Amazon and ships to the Uk. It is also a 100cm cage with 8mm bar spacing, but it has a nice big front opening door which is great for doing things in the cage and for interaction with a hamster. However it is very tall at 56cm so really needs a full level in it to avoid fall risks or quite a few shelves - and that then bumps the cost up. I very nearly got this but went for the Barney as it already comes with a shelf, isn't too tall (if you fill the base with substrate to reduce the full height a bit), and because I find it difficult setting up tall cages - plus it can get quite expensive in shelving. If you don't mind a bit of diy, making a full level is the cheapest way to go, with access at one side and a shelf over that access section. I think it works out about £70 including postage.
https://www.amazon.de/M%C3%A4use--un...words=Borneo+L
It actually comes in a 120cm version as well! Also with 8mm bar spacing - I think it's the only 120cm cage there is with narrow bar spacing.
https://www.amazon.de/M%C3%A4use--un...words=Borneo+L
It also comes in another version with a couple of shelves and a different coloured base - the Speedy Gonzales (also in 100cm and 120cm)
https://www.amazon.de/Skyline-2423-G...peedy+gonzales
https://www.amazon.de/Skyline-2983-G...peedy+gonzales
But these cost quite a bit more just for a coloured base and a couple of shelves and ladders - and still need more shelves or a full level.
I would love a 120cm cage, but 100cm is good and works really well for our Syrian - now he is older and can't climb it means he has a good amount of floor area in the cage to use and there is enough floorspace to take his toys and so on off the shelves and have them at floor level. I also had an 80cm cage before and found it not quite big enough for our large Syrian. One thing I like about the 7mm bar spacing is the substrate doesn't fall out
I have it piled high against the bars in some areas, so you can have it quite deep for a bit of burrowing - our hamster also piles it up against the bars in a big mountain sometimes, so it helps that it doesn't all fall out!
If you prefer tank style cages and don't want much diy, then as well as the detolf there is the Living World Green eco Habitat which comes in 100cm and 120cm sizes and the 120cm one is a massive 120cm by 75cm deep. (I think internal is 115cm). The lid has large 2cm slots though so they could do with meshing or a hamster could escape - these are also quite expensive though. I actually did a video of my 10 favourite hamster cages this year, which gives a a few pros and cons so that might help. It doesn't include the larger ones mentioned here but shows a few other cages as well.
https://www.youtube.com/watch?v=JSKzn0g3sVk