If you are in the process of acquiring your first pneumatic nailers, then the Bostitch kit (available from Lowes and elsewhere) is a nice starter set. A couple years back I purchased their kit which included a 6-gallon compressor, 16-ga Finishing nailer (2-1/2"), 18-ga Brad nailer (2") and 18-ga Narrow Crown (1/4" crown, 1-1/2") stapler for about $279.
Since then I've also added the Bostitch 23-ga Pinner and a 21-ga EZ-Fasten (Woodcraft) Pinner/brad nailer, both of which support up to 1-3/16" pins (30mm).
I really don't have any complaints with regard to any of the nailers (other than to say that Grex 23-ga pins generally fit the Bostitch 23-ga Pinner better than Bostitch's own pins, except for the 3/4" Bostitch pins, which fit better because the Grex 3/4" pins are 1mm too long -- go figure!). I have not had any problems with any of them and jams are very rare (but easy enough to clear on the very rare occassions they occur).
I took advantage of the Bostitch package mostly for the nailers, and as an opportunity to acquire a portable compressor. At some point in the next year or two I will upgrade to a 60-80 gallon 4-5HP air compressor for my shop, and will keep the 6-gallon Bostitch compressor for portability.
All 5 of my nailers are of the oiled-type and I find 2-4 drops of oil before each task keeps them all happy. I have not tried any of the oilless type nailers as of yet.