I would've got the OP7Pro if it was actually easy to get the 12GB model here with a contract and not having to pay outright. That's only reason I got the S10+ over the OP7Pro.
Amazing display with an optical under-display fingerprint scanner, pop up camera might take some getting used to, got a hardware sound toggle, camera is good for the price, OxygenOS is ridiculously fast in general as it's really well optimised. UFS 3.0 file transfer is great too. Absolutely no bezels, HDR10+, 1440x3120 screen that runs at 90Hz. Fairly large 4000mAh battery that can charge at up to 30W. Recharging the phone if you need to will not be an issue whatsoever.
It's also got a Snapdragon 855 processor which is crazy good, better than what you'd get in the Samsung (in Europe! We only get Exynos for Samsung :C)
A few downsides, however, would be non-expandable storage, no wireless charging and no headphone jack.
Another positive is the PRICE.
Samsung Galaxy S10/S10+
If you don't want the OP7Pro, the S10+ is an amazing choice too. It has many things the Oneplus has and some things are better. For instance, the screen is pretty much just as good. Same resolution, HDR10+ but doesn't run at 90Hz and has a cutout for the camera (the hole is slightly larger on the Plus model). The fingerprint sensor on the S10 is also under the display, is just as fast but also more accurate as it is ultrasonic and not optical. As well as this, the S10+ has expandable storage, a headphone jack and wireless charging capabilities.
Software-wise the S10/S10+ is also super snappy and really fast but not quite as good as the OP7Pro
Battery life may not be as good as tests have shown that the Exynos model S10+ you get in Europe isn't as good as the S855 model you get in the US. That being said, the cameras are slightly better on the S10+ despite OP getting a recent camera software update which worked wonders. The S10/S10+ also have official waterproofness ratings and are rated at IP68, the OP7Pro does not have an official rating for water/dust-proofness probably due to the pop-up camera.