The absolute best place you're going to find good information about ABS vs PBT, Laser vs Engraved, Doubleshots, etc...
All About Keys wikiI know that sounds like I'm brushing off your question, but as I started to answer specifics, I realized that's better written and indexed for you.
My personal preference between those two would be PBT engraved. (PBT = nicer IMO, and laser etched fades fast anyway)
I don't know much about the 7G layout. Congrats on the HHKB Pro2!
And welcome to geekhack!
PS: We're currently running a
group buy for RGB modifiers if you're interested!