We are taking pot-shots at what he might like... but we don't know the driving style!
The Si version of the civic had a stiffer, firmer ride than the non-Si counterpart. So that "oem" ride will likely NOT be the same as a monroe or gabriel offering, which will likely be in the general ballpark of the non-Si version of this car.
The suspension, IIRC, may also use progressive-rate springs, with non a whole lot of travel... so going underdamped could result in some body bounce.
So it all comes down to what do you want? Is this more of a commuter vehicle where you want a smoother, more comfortable ride? or are you in the habit of slinging it through a few corners?
If it's a softer, smoother ride, I would consider upper-end monroes (or gabriels). they will likely be a bit softer than stock, and softer than the KYBs. if you like carving through corners, bilstein would be a safe play, and possibly tokiko... (they used to at least make some good dampers for these cars). I would NOT settle for the budget-priced monroe/gabriel offerings. they may wallow a bit too much with the progressive springs and lightweight car.
I had kybs on a 97 legacy. stiffer than stock, and a little harsh. oem bilsteins on my truck are about as stiff, but not as harsh. monroe reflex shocks on my minivan are much more controlled than stock, not harsh at all--- may be my favorite, actually, but they don't make the reflex for everything.
m