I am getting ready to run lines in my 2 car garage as well. Well I will be just as soon as I settle on what I want. I am going overkill on outlets though. Going to have probably 4, but possibly 5 (one on each side of the garage door, one at my work bench, one for a reel by the garage door opener & probably one by the man door into the house which would basically be the 4th corner of the garage).
Here is what I am considering so far.
1/2" PEX - This would be the fastest & easiest. Easily available parts locally & very flexible system as far as adding on or moving/removing legs. Not really rated for air though, but with my system regulated to ~110 or 120 PSI shouldn't be an issue.
PEX-AL-PEX - More expensive then PEX, but not so expensive it would break the bank. No new tools needed since I have plenty of good wrench's for the compression fittings. Better PSI rating so I wouldn't have to worry if my regulator died on a hot summer day & pressurized the lines to my compressors 175 PSI max. Parts would all have to be ordered, but between Amazon & Ebay I would be into it a little under 200 bucks & with the smallest roll of PEX-AL-PEX being 300 feet I would have enough left over to sell it to my neighbor so he can do his too.
1/2" Copper - I have never sweated copper before otherwise this would probably be the obvious choice as it doesn't have the drawbacks of other's, but its also not as flexible for my ever changing garage. I also have a couple of places where I would have to jog over & add fittings to clear obstructions where the other materials would just flex around.
For any of them I plan to just use a 90 drop ear elbow for the outlet itself. I will have to drain with just an air nozzle, but at least 2 of these outlets (the ones I would use the most) will be right above electrical outlets so that method is preferred over a drip leg anyway.
For my overkill desired system with any of the above options I will be less then 200 bucks into it. The cheapest being the regular PEX @ ~150 & the other 2 coming in at just under 200 (including the tools that I dont own thats needed for whatever method I choose).
For the Filter/Regulator I looked at the Klutch stuff, but since my compressor puts out considerably more then its rated 145 psi I would rather error on the side of caution. Thinking of going with
this one from amazon for about the same price.