Ok so, I had issues with generic readers corrupting files, so I compared the SanDisk ImageMate PRO USB-C Multi-Card Reader/Writer against cheaper brands. The SanDisk is highkey faster and more reliable for those 30MP files. Also, I'm kinda disappointed with the stock strap for pro work. I prefer the Peak Design Slide Camera Strap Black over the original. It’s way better for your neck during long days. So yeah, focus on reliability and comfort!

For your situation, I honestly think getting the right plate is huge. I learned the hard way that cheaping out on gear for this body is a mistake, realy. Here is what I recommend:
* Really Right Stuff B5D4-L L-Plate vs generic brackets: I tried a cheap knockoff brand first and it kept slipping during portrait shots. So annoying! The RRS is pricey but it actually stays put, whereas the cheap ones are just wierdly loose. * Vello Screen Protector Ultra for Canon 5D Mark IV vs thin films: Skip those flimsy plastic films. I had issues with bubbles and peeling after just a month. This glass one feels like the actual screen and has saved me from some nasty scratches. So yeah, basically dont waste money on the budget stuff like I did. Definitely go with the Really Right Stuff B5D4-L L-Plate if you do any tripod work, it’s a total game changer. gl!

Congrats on the pickup, it's a solid choice for sure. Before I dive into more gear tho, what kind of pro work are you actually planning to do? Like is this mostly indoor studio stuff or are you gonna be out in the elements? If you're looking to save some cash and keep the body in top shape without sending it off to a shop every few months, you basically gotta learn to do your own maintenance. It's not as scary as it sounds and saves a ton of money over time. * Giottos Rocket Air Blaster - This is the gold standard for getting dust off the sensor safely without touching anything, yeah dont use compressed air cans.
* VSGO Full-Frame Sensor Cleaning Kit - Get this for when the blower doesn't cut it and you need to do a wet clean yourself. Doing your own sensor cleans is a game changer honestly because you don't have to wait two weeks for a service center to send your body back right in the middle of a busy season. Just gotta be steady with your hands tho.

This ^

Can vouch for this

So, congrats on the body—the 5D IV is still an absolute workhorse for pro-level work. From a market perspective, you really gotta be careful with the flood of generic third-party power solutions out there. When you're looking at external power or even vertical grips, the communication protocols between the accessory and the DIGIC 6+ processor are super sensitive. Honestly, I've seen way too many people try to save a few bucks on off-brand battery packs only to have the camera throw "communication error" codes right in the middle of a shoot because the chip inside the accessory isn't properly handling the Canon handshake. Basically, if you’re doing pro gigs, avoid the bargain-bin stuff that doesn't strictly adhere to the original voltage specs. The 5D IV has a pretty high draw, especially if you're using Dual Pixel AF or 4K logging. Also, be wary of any accessories that might compromise the weather-sealing gaskets. I’ve noticed a lot of the cheaper mechanical accessories don't have the same manufacturing tolerances as the high-end manufacturers, which kinda defeats the purpose of having a weather-sealed body. Just stick to the reputable brands that actually publish their tolerance specs; otherwise, you’re just asking for an expensive repair bill later on.