Yeah, if the 5070 had 16GB it would be an easy choice for a 'modest' budget, but they're upselling to the Ti and the 5080.usually there is a stand out choice to me and i just buy that but as i have shown above there are positive and negative.
i partly blame Nvidia for the Lack luster specs this generation ( and last) with no clear winner and certianly no value for money.
The 5060 Ti 16GB isn't a bad card for creators, but as you noted, the performance is a pretty hefty chunk lower.
I don't do any development work in UE5, but from what I'm aware, VRAM for workstation usage tends to be: "enough = good", "not enough = very bad", with less performance just annoying rather than showstopping. So, I'd personally lean toward the cheapest 5060 Ti 16GB you can get (that doesn't have a bad cooler).
The Prime looked pretty good in TPU's review, they used pads for the backplate/memory, the backplate is metal, the fans are ball bearings, it runs very quietly and it has a dual BIOS. It is also available just above £400.