This is probably one of the more frequent questions that I hear. For the most part, I get asked this question by beginner photographers, which is fine of course. Unfortunately, it's not always easy for me to give a straight answer, because there are a lot of factors to consider. Despite this, I think this video may help provide some answers.
A recent video from Matt Granger discusses this very topic. The video aims to answer some of the questions many beginner photographers may have when deciding on camera systems. With all the different makes, models, and brands to choose from, it can be a little overwhelming. The main point that Granger makes is how second hand equipment can be brilliant options for people starting out or photographer looking for the best value for their money.
Cameras that were released five or more years ago, haven't suddenly become worse. These cameras are still as capable as the day they were first released and they were the best at their respective time. I think buying a second hand camera from a reputable retailer, can be an excellent way to get some of the best equipment for very little; in comparison to buying brand new current camera models, at the same price.
Check out the full video linked above to see some of the equipment tested and recommended by Granger.
The one you can afford with cash :-)
Lots of cameras sit at similar or the same price point.
As far as old cameras I would agree cameras like Sony A7 and Fujifilm Xt-1 is not worse then a few years ago, but are rather terrible anyway:)
This horse has been dead for years. Used vs new anything. Save money by buying used and regret it later. Used cars, used computers or cell phones, used furniture or just about anything used cost less than new. So what? If you can afford it buy new and latest and you'll never regret it.
The last camera I bought was mint condition with 3,000 actuations; it was also $3,000 cheaper than its new price.
It's just a question of being patient and spending the time looking.
I've never been burned by used camera bodies before. If you're on ebay, you just wait for a listing by a seller with ≥ 99.8% positive feedback where the camera is in very lightly used condition and it'll almost always be solid. Then, you snipe the auction and only bid during the last ten seconds, like a respectable buyer.
I've been much less lucky with second hand or grey market lenses. With the above ebay strategy, they're actually in fine condition when they arrive, but if you get sand in them or they develop issues from travel, not having the warranty to cover repairs becomes pretty expensive, plus, you don't save as much money buying used lenses as used camera bodies. YMMV depending on how you treat your gear I guess.
I have seen fine art work done with a pentax k1000 and snap shots with a hasselblad. The camera brand is not important
Buy the one you would enjoy shooting and carrying, so you would't want to search for other options. Good luck!
P.S.
Might agree on D4s, S2 is a tricky choice - you really have to know what you are doing: superb camera with some significant issues reported (some users experienced sensor, focusing motor or mirror mishaps)
Plus one for the D4/D4s, especially if your into action photography and you have enough lens. If you're not into action photography and on a budget the D810 is a phenomenal deal right now. I think it has much better than Canon 5D Mark IV image quality and performance, since it has the D4s AF system and it's less money at around $1100 used. If you're into wildlife and on a budget you can't beat a used D500 and 300mm f4D AF-S or a Canon 7D Mark II and 400mm f5.6L! For landscapes right now I think you'd be crazy to not buy a new or used Fuji GFX50r as they are around the same price the D850 was selling for not long ago. Right now has to be the best time in history to be buying used camera gear. There are some amazing deals right now and I've recently had the pleasure to buy a D5 and a 24-70mm f2.8E VR lens. Both are like new condition, the D5 has only 30k shutter count and I got both for $5000! Both were USA models too!