hi, educate me (BMW wheel shopping)

I’m attempting to assist my Brother in-law with replacing his factory 16in wheels on his 2008 238ix with something 17 or 18, preferably in a darker colour (dark grey, gunmetal, black). Anyway, that’s the request from the “client”, but I’m a bit of a noob all things BMW.

so I know I need something 5x120, preferably something OEM, but he’s not opposed to aftermarket. I need a square setup, so nothing staggered from the M-series.

‘08 has TPMS?

Anything I should be avoiding? non-OEM brand wheels needing hubcentric rings etc?

Any non-BMW brands of wheels that I should hunt for, known for being a good fit and quality?