In my experience, making the jump to a full-frame body like the 6D Mark II really highlights why you need a reliable speedlite, especially since there's no pop-up flash to bail you out. Honestly, I spent years messing around with expensive official gear before I realized third-party stuff has basically caught up. The big thing you gotta look for is the communication between the flash and the camera's autofocus system. The 6D II is great, but in dark reception halls, you NEED that AF assist beam to be accurate or you're gonna hunt for focus all night. Also, E-TTL is non-negotiable for events cuz things move too fast for manual mode. High-speed sync is a lifesaver for outdoor portraits too, so I definitely get why you want that. For your $250 budget, you should LITERALLY skip the Yongnuo stuff and go straight for the Godox V1-C Flash for Canon. I've been using it for years and I'm so satisfied with the results. The round head gives a much softer, more natural falloff when you're doing direct fill or bouncing off a ceiling. The real reason it wins tho is the lithium-ion battery. Traditional AAs are such a pain and the recycle time slows down as they die. With the Godox V1-C Flash for Canon, the recycle time is super fast and stays consistent until the battery is empty. It supports E-TTL II and HSS perfectly. If you want a more traditional shape, the Godox V860III-C Li-Ion Flash for Canon is pretty much the same beast and works just as well. Its honestly the best bang for your buck. Good luck!!

Quick question - what kind of glass are you mostly rocking for these receptions? Before I give advice, I gotta know if you’re shooting with f/2.8 zooms or faster primes like a 50mm or 85mm. The reason I ask is because the AF assist beam on third-party units like the Godox V860III-C Li-ion Flash for Canon can sometimes be slightly offset compared to the 6D II’s specific focus point grid, and it makes a HUGE difference if you’re shooting wide open at f/1.4 vs f/4. I've used the Yongnuo YN600EX-RT II for Canon and it’s a decent budget option, but the recycle time can be a bit sluggish when the batteries get low during a long set. On the other hand, something like the Godox V1-C Flash for Canon uses a lithium battery which is SO much faster for those back-to-back candid shots. Honestly, E-TTL II is great, but HSS really drains the juice, so battery type matters a ton. Let me know your lens situation and I’ll help you narrow it down!

So basically, the consensus is that third-party units are the way to go for the 6D II if ur trying to save cash, but the AF beam alignment is the big risk. I’ve been looking at the market specs and honestly, the biggest brand difference right now is the battery tech. Like, the Godox V860III-C Li-ion Flash for Canon uses a proprietary lithium battery while the cheaper Yongnuo YN600EX-RT II for Canon still relies on 4x AAs. From what I’ve read, the recycle time on those lithium packs is basically twice as fast, which is huge for candid shots. But I’m still a bit of a beginner, so I wonder—does the extra heat from faster recycling hurt the flash longevity? Also, have u looked at the Godox V1-C Flash for Canon? It has a round head which is supposed to give a more natural light falloff for portraits. I’m not 100% sure if the difference is noticeable indoors compared to a traditional rectangular head, but it’s right at the top of ur budget. It’s wild that a $230 third-party flash has specs that compete with the $500+ Canon stuff. Not 100% sure if the build quality holds up over years of use though.

> the biggest brand difference right now is the battery tech. Tbh, couldn't agree more. Those Li-ion packs are a literal lifesaver during long receptions. But coming from a DIY enthusiast background, there’s another huge plus to the third-party route like the Godox V860III-C Li-ion Flash for Canon that people often overlook: self-service maintenance and firmware updates. If you buy a Canon Speedlite 600EX II-RT and encounter a weird AF assist bug or communication error with the 6D Mark II’s specific sensor layout, you’re basically looking at a professional service center bill to get it looked at. With Godox, you handle the 'service' yourself via the USB port. I’ve actually solved minor AF grid offsets on my own just by downloading a patch and doing it myself—it’s way more empowering than being at the mercy of a manufacturer's repair timeline. Also, if you're worried about that $250 limit, lean into the DIY side of modifiers. Instead of buying a $50 'pro' diffuser, I still use a DIY white card and rubber band for bounce. It works wonders with the 6D II’s full-frame sensor since you can push the ISO a bit anyway. lol.

> I definitely need something that supports E-TTL II for accurate metering and has High-Speed Sync (HSS) Like someone mentioned, that 6D II can be a bit finicky with the hot shoe connection. Just be careful when you're mounting whatever you buy, make sure to check if the pins are lining up right or you might get some weird E-TTL errors mid-shoot. You might want to consider lurking on the Strobist blog too, it's a huge resource for learning how to rig up cheap gear to look like a pro studio. Honestly, this brings back memories of when my uncle tried to be the pro photographer at a family reunion with an old manual flash he bought at a garage sale. He didnt realize the trigger voltage was way too high for modern digital bodies and he literally saw a spark fly when he took the first photo. The camera just died right there in his hands. He spent the rest of the day trying to explain to my aunt why their expensive new camera wouldnt turn on anymore... it was a total mess. Just make sure you double check those specs before you slide anything onto that 6D II hot shoe so you dont end up with a very expensive paperweight!

Ok so, jumping in here cuz I totally feel u on the 6D Mark II low-light struggle. I've been rocking that body for a couple years now, and honestly, the lack of a pop-up flash was a major shock at first. When I started doing receptions, I was reallyyy worried about spending a fortune on a single light, so I went the third-party route instead. In my experience, the technical trade-offs are actually pretty manageable if you know what to look for:
* The E-TTL II metering on the setup I use is surprisingly accurate, though I usually have to dial in a bit of flash exposure compensation (FEC) depending on the ambient light.
* Recycle times are the real deal-breaker. The unit I got uses a lithium-ion battery instead of AAs, and it's SO much faster... basically keeps up with my bursts without breaking a sweat.
* HSS works fine for those outdoor portraits, but just remember it kills your power levels fast cuz the flash is basically pulsing at a high frequency to match the shutter. I did notice the AF assist beam on some of these cheaper brands can be a bit hit-or-miss with the 6D II's specific sensor layout. Sometimes the red grid doesn't align perfectly with the outer points, but for center-point focusing, it's usually fine. I guess it just depends on your needs, but for $250, you can definitely find a setup that out-specs the base-level official gear. It's been a solid way to keep my kit within budget while still getting professional results. gl!