In my experience, weddings are too chaotic to mess with loose cables. I've tried many over the years and these two are solid:

• PortKeys LH5P II 5.5 inch 2200nit Monitor
• My top pick. It controls the S5II wirelessly so you dont need to touch the camera screen. Super bright too.
• Atomos Ninja V 5 inch 4K Recording Monitor
• The classic choice. Very reliable if you use a decent Kondor Blue Braided HDMI Cable. I'd go PortKeys, honestly.

^ This. Also, I'm satisfied with the Osee T5+ 5.5 Inch 1000nits HDMI Monitor. It's a cost-effective choice that provides professional calibration tools and a very stable signal.

Adding my two cents because I have seen too many shoots ruined by gear failure... ceremonies are stressful enough without your screen going black. Before diving into a new purchase, I gotta ask—are you using a full cage with a dedicated HDMI cable clamp? I have found that even the best monitors will flicker if that tiny port isnt locked down tight. Not totally sure if this applies to every model, but I have heard some things that might be worth looking into:

• I think some screens have a weird power draw that can mess with the S5II battery life if you are looping power
• Someone told me that certain brands have a bit of a delay or lag when switching between recording and standby
• I recall reading that firmware updates on the camera can sometimes break the remote control features on third-party screens I am always a bit nervous about trying new brands right before a big wedding, so definitely test whatever you get for a few hours straight first. Let me know about the cable clamp tho, that might be your real culprit.

late to the party but ive been through this exact headache with the s5ii. the hdmi connection on these cameras is basically the weakest link in the whole chain. honestly, if your colors are off, it sounds like you need better calibration support rather than just a brighter screen. the s5ii sensor is killer but if your monitor is shifting the tint, you're gonna have a bad time in post. heres a few things ive learned after shooting dozens of events:

• look for high nit counts, like 2000 plus, so you can actually see what youre doing outdoors in chicago.
• focus on brands that prioritize color accuracy over fancy recording features you wont use.
• definitely invest in a proper cable clamp because that loose port is gonna kill your signal regardless of the screen. i would honestly suggest looking at anything from SmallHD or maybe some of the newer panels from OSEE. in my experience, their color science is just miles ahead and they handle the lumix signal way more reliably. you dont really need a recorder like the ninja unless you're actually shooting raw, which for a wedding is probably overkill and just adds weight. just get a solid high-brightness display from one of those brands and you’ll be much happier... they just feel more professional in the hand too.

Just saw this thread and wanted to share my experience because I went through a similar transition. My previous monitor constantly struggled with color accuracy, making it impossible to trust the V-Log output on my S5II. I spent weeks analyzing technical data sheets and eventually switched brands. The one I got now has a much more efficient processing chip that significantly reduces input latency, which is crucial for manual focusing during fast-moving scenes. I've been extremely satisfied with how it handles the 10-bit signal without any flickering or artifacts. During a recent twelve-hour shoot, the heat dissipation was incredible; it didnt throttle once, unlike my old gear. It really taught me that the internal hardware and signal processing capabilities of the monitor are just as important as the camera sensor itself. The color gamut on this unit matches the sensor profile much more naturally, so I dont feel like I'm guessing in the field anymore.