don't have a 99 but have a base '97 and my roomate has a '00 Gsr. The integra is a very nice car. the weight aspect helps the integra over the prelude. the b18c is also a sweet motor. The torque of prelude's h22 helps too. The prelude is a more solid car. more luxury. from a sound stand point, the car is very insulated, which is a nice enhancement for the nice stock system. I like the driving position in the prelude much better than the integra. the teg feels more like a civic with a nice motor(which what it basically is). The prelude is more value for the money.
one thing about tegsthough, they look nice stock, with the stock ride height and their little 15inch rims, compared to preludes which look disporportioned stock(In my opinion anyway). but put a set of 18s(or17s) and drop a prelude and I think it looks way way better than a teg with the same done. try to find a 5spd though.
not to start anything but it really doesn't matter if they are common or not and it's 'common' knowledge that preludes sold only about 11,000 a year which is nowhere compared to the amount of tegs sold. I would actually like if there were more fifth gen owners around me, to share more info.
The 5th gens are really nice cars, from design, comfort and performance standpoint, although they are overlooked for tegs and civics. if you were to drive a prelude and then drive a gsr, it would feel like a downgrade.

I say go for the Prelude!!