I like the Minotaur MTAC, adjustable height/cant/retention with replaceable bodies. I like the idea of having one holster for all my guns. Never comp'd with it though.
For games, the Bladetech DOH is pretty popular in production division. You can remove the drop/offset attachment and then it's IDPA legal and very good holster for that game. It won't conceal so great, but it'll work in a pinch.
The Raven is a great concealment holster, and I was using mine for an M&P for a bunch of the matches early in the season. It will be slower on the draw than the Bladetech because of how close it rides to your body, but for that same reason it will conceal better.
Is kydex really that "bad" for the finish? The finish is going to wear, especially if you practice with any frequency. Get used to it. Honest wear looks cool anyway.
What are you using for the above applications? Bladetech DOH for USPSA, homemade Raven style for carry and IDPA
What are better single or double mag carriers for competition? Best brand? I prefer single for more latitude in placement and spacing. Comptac for IDPA, Bladetech for USPSA I have a dedicated belt for USPSA with holders set up for that wider belt. The comptac stuff is set up for 1.5" belt. The bladetech stuff with the Teklok attachment can be adjusted to belt width,, but I don't like pulling my rig apart. The comptac holders are non-adjustable.
Belt recommendations? Width? Depends on the game. USPSA the inner/outer belt rigs are popular and what I use, a CR speed to be exact. For IDPA, its my carry belt, which is a 1.5" normal looking thick leather belt. The inner/outer belts aren't legal in IDPA, if I remember correctly. Even if not, the IDPA Tactical Timmys will shun you for being a gamer.
any brands I need to consider that I didn't mention? Bladetech.
I went with a shooters pack from BladeTech. You get a sting ray belt holster, paddle attachment, and double mag pouch. They are IDPA approved as well. It's the best kydex holster I have owned to date.
You had mentioned price being a concern. I picked up a Tagua OWB for less than $40 at Indy Trading Post and so far it has worked great for me when CC. I'm not a big fan of IWB holsters, but that's just me.