between the 06-09 the rsx has a nicer body and is alittle lighter then the civic so better mpg. the only thing is i would get an 04 rsx as it is the same but the headlights are alot nicer they have that little bubble to them that causes them to push down into the bumper kinda like the new mercedes have for the headlights.
id also look into a 01-05 civic coupe the body is nicer then the newer ones and you will save a good 8-10k when getting it.
id also look into maybe a 99 honda integra gsr those are really nice and would blow the rsx out of the water plus any honda or acura area really reliable cars. and you can find a nice one for about 3k-4k