>>166463>>166740>>167197etc.
Mechanical disks are simpler, easier to set up. I've rebuilt hydraulic calipers when the square o-rings fail, the piston gets stuck on one side, and contamination/corrosion always finds it's way in. It's especially nasty with DOT fluid systems, which absorb water. Meanwhile my other bike has had Avid mechanical disks for 9 years with only pad changes, so I put them on the new one. I chose 180mm disks for more rotational leverage, so there is more stopping power with a little less hand pressure.
The rear derailleur is part of the SRAM 2x10 system. I got it almost new from a local mechanic who pulled it off a new bike and replaced it, before he rode it, with something else, so I got a good deal on it, like half price.
This is deliberately a "middle of the road" bike price-wise, but I splurged on really light tubeless rims, which is where spending money counts. This thing floats over everything.
My original pic was when the bike was just put together, and I have moved stuff around since then. New low-res-phone-pic related, up on top of one of the local bike trails.