For the record I have a late-2008 Unibody MacBook Pro 5,1, and it still works just fine. Technically it's my most modern Apple computer (not counting tablets). I've swapped the hard drive for an SSD and moved the hard drive into the DVD bay. The SSD has MacOS Mavericks and the hard drive has Snow Leopard, because Logic Express 9 doesn't work with Mavericks.
You have to use DosDude's popular patch tool to get Mavericks working. Off the top of my head the contemporary unibody MacBook - the non-pro version, just the standard MacBook, albeit that it had the same body - doesn't work with Mavericks as well because the wifi card is different. I could be wrong.
The late-2008 model is relatively easy to work on because the hard drive and battery are under a lift-off flap, and the battery is a separate unit. It has two GPUs. The discrete GPU is faster but I never use it because from the perspective of 2019 it's still not fast enough for games and it just makes the machine hotter.
From a used point of view I suspect that the Nehalem models - e.g. the i5, i7 models that replaced the Core 2 Duo - that came out from 2010 onwards are a better, more future-proofed choice.
As for screens it's hard to judge because the newest PowerBook is fourteen years old, but the screen on my high-res 17" PowerBook G4 is matte (which is good) but noticeably yellowy-er and less contrasty than the screen on my MacBook Pro. It's usable, and perhaps it has faded over time, but it's not as good. The MacBook Pro's screen is still good by modern standards although I hate the fact that it's reflective.
