A lot of it depends on how much you plan to use it. I have a 5hp 30gal horizontal one that works well for the few times a year I use it (driveway :-( )
Now if I had a garage I would probably get mthing with a bigger tank.
As fas as brands go in all honesty most of the homeowner compressors are made by the same people. So that is not much of an issue.
mine goes to 125 and kicks the compressor back on at about 85psi. it works well for the impact gun, air hammer, etc. a DA sander or heavy use of the cutoff wheel taxes it though.
The most important thing to do is get a really good compressor, with air filters and a built in or external regulator. This will keep your air tools from crapping out on you from too much PSI and dirty air.
For air tools, get what you need at harbor frieght. I have had mine for a while now, and they last a long time. The important thing to do is to oil your air tools once a day for every day you use them. That will prolong their life.
Don't get the bottom of the line impact gun or ratchet, get a couple steps up. It will increase the effeciency of the air that it uses, so you won't be running your compressor as much.
Scott
funny you should have this post. i was wondering the same thing, so i did some research, an it all depends how much you use it, and for what. i just need it for little stuff here and there, but i also wanted to paint my bike and do a bit of more indepth stuff. anyway, i found the perfect deal. craftsman 6hp, 150 psi, external regulator, 33 gal. for 300. AND it came with ratchet gun, impact gun, and air hammer with hose for free(the tools are of really good quality, not that plastic ****).