To the OP, your needs seem to indicate a need for a 15/16 ga. finish nailer AND an 18 gauge brad nailer. A 23 gauge pinner might come in handy down the road for glue ups, but wait until the need presents itself. If you were buying one, cordless would be a great convenience despite the price, however, if you're going to buy more than one, the cost of the cordless guns gets prohibitive. The air guns are lighter too, which you'll appreciate if you're doing extensive overhead work. If you were going with two guns, I'd recommend an angled finish nailer (angle helps you wrestle the bigger gun into corners and stuff) and a regular brad nailer. Make sure you can readily get the nails your guns require at your local HD or Lowes. Bostitch has a 7 year warranty on their guns now, and all mag construction for lighter weight. Dewalt is good (I got a refurb from CPO), Hitachi is a great value, Porter Cable is an old stand by for many (packaged with a compressor, you often get a great deal). If you're doing fine finish work where you don't want oil marking up your surface, consider an oil free nailer. They won't have the longevity of an oiled nailer, however, for homeowner use it's not likely to matter. My dewalt can be run with oil or without. Usually I put a few drops of oil in there, unless I'm concerned about marking up the wood, then I'll go without. You might still get a little oil trace, but much less than if you had added oil to the gun before working. As for compressors, generally the oiled will last longer and will be quieter, but I think Dewalt makes a pretty quiet and compact oil less compressor.
I've got a Makita oiled compressor, Dewalt angled finish gun, Milwaukee brad, and bostitch pinner and stapler. I'm very happy with all of them, and none see more than typical homeowner use. Among the guns the dewalt is probably my favorite. Just the way it feels in the hand, quality of construction, etc. But I've not had an issue with any of them really.