The biggest part of computer and IT work is the physical tools you have. What is your toolkit and what tools do you recommend? Currently, I have a screwdriver and the bits required, along with a key remover and other tools I have in storage.
Nexus 5s are cheap, repairable, and badass. Hope you know how to microsolder, there are always plenty on eBay with bad power buttons and you'll have to replace yours someday.If you have a smart phone, spend about 20 bucks and buy yourself another digitizer, screen, and all the nice little tools that let you open it up and replace parts. You'd be amazed how much money you'll save on repairs from a store or (god forbid) the manufacturer and how much more life you'll get out of that device.
Unless you've got one of those newer phones where everything on the inside, including the battery, is fucking glued together; in which case, just save yourself the trouble and put a bullet in your brain.