Over the years, I've been quite pleased with the following for my Glock G17:
-Blade-Tech IWB
-Safariland 5181 paddle
-Glock Sport/Combat beltslide
-Glock Sport/Duty
-For situations where absolute minimal profile is requisite, at the cost of ease in reholstering, Bianchi Professional 100 IWB
-For situations where the most complete protection to the pistol is ideal, a Bianchi UM84/M12 flap holster or Wilderness Safepacker
The two Glock polymer holsters, especially the Sport/Combat are surprisingly effective, and quite inexpensive. If you're looking for an acceptable and effective "starter" holster while you're refining your holster tastes and requirements, I'd suggest going with the Glock Sport/Combat. I stil find mine to be a quite good OWB holster.
For magazine pouches, I prefer The Wilderness' Double Ugly for IDPA, and one of their single magazine pouches otherwise.
Best, Jon