OnePlus 15 vs Vivo X300 Ultra

OnePlus 15

Snapdragon 8 Elite Gen 5 with up to 24GB RAM and a custom tri-chip setup — it tops benchmark charts, beats the iPhone's A19 in multi-core and runs games at up to 165fps. The asterisk is sustained thermals: day-to-day it stays cool, but extended stress benchmarks repeatedly overheat and shut down.

• Across a benchmark suite the OnePlus 15 performed 19–22% better than the OnePlus 13 and 14–19% better than the S25 Edge, and outperformed the OnePlus 13 by 10% in the stress test.
• Geekbench shows the Snapdragon 8 Elite Gen 5 easily beating the A19 with a multi-core score over 11,000; in Genshin Impact it averaged 119fps vs the iPhone 17's 107fps over 30 minutes, running cooler at under 36°C.
• BGMI runs native 120fps (165fps with frame interpolation) at under 35°C and under 4W power draw, making it one of the best phones for gaming with its 165Hz panel and bypass charging.
• In a 15-minute 20-thread CPU throttle test it throttled to 82% of max performance at a controlled 34–35°C with only 3% battery drain.
• It flashed an overheating warning after barely 8 minutes of a peak-load benchmark, shutting it down and disabling the flashlight and hotspot — though in day-to-day use it runs smoothly with only moderate warmth.
• In Wuthering Waves it held 60fps until ~46°C then capped to 45fps and recovered after ~3 minutes, averaging 57fps and 7W — heavy sustained 3D load is where the thermal limits show.

Vivo X300 Ultra

Snapdragon 8 Elite Gen 5 plus Vivo's custom imaging silicon delivers flagship benchmark numbers and strong gaming, but the camera-heavy hardware runs hot — sustained stress tests show roughly 60–65% stability and the camera app warms it up fast.

• At the heart is Qualcomm's current flagship Snapdragon 8 Elite Gen 5, supplemented by Vivo's custom VS1 and V3-Plus imaging chips.
• It boots in 16 seconds (vs 21s for the S26 Ultra and 19s for the iPhone 17 Pro Max) and posts an AnTuTu score over 3,800,000, stronger than Samsung.
• In a prolonged stress test it throttled CPU performance to about 60% of peak — in line with other high-powered flagships — and 3DMark stability landed around 63–66%.
• It gets a bit hot after 30–40 minutes of gaming, but with no throttling even past an hour and never uncomfortable to hold; boost mode at max graphics gives around 4 hours of Wuthering Waves on a full charge.
• Native 120fps gaming with smooth/very-high graphics in many titles, with temperature barely crossing 35°C and power draw around 4W in battle-royale modes.

OnePlus 15

The single biggest reason to buy this phone. A 7,300mAh silicon-carbon cell delivers the best smartphone battery life ever measured — a record ~25-hour drain test and 2–2.5 days of real use — with 120W wired charging refilling it in ~40–51 minutes plus 50W wireless.

• The OnePlus 15 lasted an insane 25 hours 13 minutes in the drain test — officially the best phone for battery life, beating the iPhone 17 Pro Max's 17h54m and lasting over 10 hours longer than the Galaxy S25 Ultra.
• The OnePlus 15 just delivered the best battery life we've ever measured — a very, very good phone and a strong value pick for late 2025.
• In real use it averaged 2 days 11 hours on a full charge, and 7–8 hours of screen-on time is effortless thanks to the 7,300mAh cell and aggressive standby management.
• 120W SuperVOOC charged 1→50% in 22 minutes, 75% in 36 minutes and a full 1→100% in 51 minutes; other tests hit a full charge in roughly 40–43 minutes.
• It also keeps 50W AirVOOC wireless charging — about 30% in 30 minutes and ~85% in 92 minutes, with the device staying cool around 34–35°C.
• The battery is so large you could cap charging at 85% to preserve long-term health and still have more capacity than a Galaxy S25 Ultra at 100%.

Vivo X300 Ultra

Vivo grew the silicon-carbon cell 10% to 6,600mAh while keeping the body the same size. Real-world endurance is strong — ~16h active-use score, ~7h heavy screen-on, 13–14 hour days with charge to spare — and 100W wired refills it in under an hour, with 40W wireless.

• Vivo increased the battery by 10% to 6,600mAh despite the phone being practically the same size on paper.
• In our battery test it earned an active-use score of almost 16 hours; 100W charging took it 0–66% in 30 minutes and a full charge in 46 minutes, plus 40W wireless. A charger is in the box except in Europe.
• On the China version I'm finishing entire 13–14 hour days with 25–30% left; the global version keeps the 6,600mAh cell so battery life should comfortably last 12–13 hours of heavy use.
• Getting nearly 7 hours of screen-on time with very heavy usage from the 6,600mAh silicon-carbon unit, with 100W wired and 40W wireless charging support.
• After a 4-hour heavy-usage simulation the phone still had ~45% battery left, which is solid by today's standards, and 100W wired charging takes about 45 minutes to full.

OnePlus 15

The most divisive part of the phone. OnePlus ended its 5-year Hasselblad partnership and moved to smaller in-house-tuned 'DetailMax' sensors: a triple 50MP wide + ultrawide + 3.5x telephoto. Some reviewers rate the results among the best camera phones; many call it a regression from the OnePlus 13 with color-accuracy and high-zoom issues.

• OnePlus's 5-year Hasselblad partnership has ended and the rear sensors are smaller than the OnePlus 13's — every rear camera sensor is smaller, which doesn't bring joy.
• The camera is consistently inconsistent — a recurring theme across reviews of this phone's imaging.
• The photos were usually just as good as the best camera phones, and in some cases the OnePlus 15 shots were the best compared to the Pixel 10 Pro and Galaxy S25 Ultra — and it's the best camera phone tested for fast-moving subjects.
• It has three 50MP rear cameras (wide, ultrawide, 3.5x optical telephoto); both it and the iPhone 17 Pro are impressive zoom shooters, but the iPhone is the obvious selfie winner.
• Zoom looks great up to 30x in good daylight, but beyond 20x it leans heavily on AI — human faces look drawn-on or flat, though buildings and signboards hold up well; 8K30 video doesn't feel sharp.
• After two to three software updates the biggest remaining camera issue is still color accuracy, with a tendency to crush shadows and pump contrast — but 4K 120fps recording is finally back since the OnePlus 9 Pro.

Vivo X300 Ultra

The reason the X300 Ultra exists: a near-1-inch 200MP 35mm main (Sony Lytia 901), a 200MP 85mm periscope, and the best ultrawide sensor on the market, tuned with Zeiss. Reviewers near-universally rate it the best-equipped camera phone of 2026 — with two important caveats: the 35mm default is divisive, and on raw image quality it's only marginally ahead of the cheaper X300 Pro.

• At the center is a 200MP main that's nearly a 1-inch sensor (Sony Lytia 901), backed by a 200MP 85mm-equivalent periscope telephoto — the phone is focused on camera quality and, even more so, video.
• Featuring three extra-large image sensors, the X300 Ultra's uncompromising camera hardware earned a solid rating — but it's hardly better than the cheaper X300 Pro in actual camera performance despite the top-notch hardware.
• I'm not sure I've seen better results from even 1-inch sensors — it's so close to 1-inch and the 35mm focal length makes for more cinematic-looking shots; the 85mm periscope is the sweet spot for portraits.
• It still holds the record for the best portrait-mode photos on a smartphone, especially at 85mm and 135mm; the 14mm ultrawide is sharp edge to edge.