Best GPU and Parts for a £700 1080p Gaming PC?

I'm putting together a gaming PC for my brother and already have a spare Micro-ATX case. The remaining budget is around £700, excluding the monitor and peripherals, although the current parts list is closer to £750. He mainly plays esports games with friends at 1080p and is coming from Xbox, so extremely high refresh rates aren't essential, but getting well above 60 FPS would be ideal.

The current build includes an Intel Core i5-12400, 16GB of DDR4 memory, a 1TB SSD, a Thermalright Peerless Assassin 120 SE cooler, and a 650W power supply. I'm open to suggestions for improving any of those parts. The graphics card budget is roughly £250, and I'm in the UK. I'm happy to consider reputable used retailers, but I'd rather avoid marketplace listings from sellers offering no returns or buyer protection.

The main cards I'm considering are the RTX 4060 and Intel Arc B580. I'm unsure how much Intel's driver support has improved, although he mostly plays mainstream games. The RTX 4060 seems suitable, but its 8GB of VRAM is a concern. Which GPU would make the most sense, and are there any other changes I should make to the build?