Foresight Imaging Accustream Express 170
Got this board relatively cheap (less than 100 USD). On paper this looks like a perfect solution - it can capture nearly everything - DVI, HDMI, VGA (RGB & YpBpR) up to 1080p60, PCI-e, Win10 drivers, pass-through. More recent versions of this board have native HDMI, S-Video & Composite inputs, but no pass-through.
Haven't thoroughly tested it yet, but few downsides so far:
Input-lag on capture (maybe half a second, pass-through is ok) - probably true for all capture cards?
Signal auto-detection don't work with resolutions lower than 800x600 - needs to be configured beforehand. Awaiting answer from manufacturer about this.
Blurry image in OBS due to slight resolution mismatch, not sure if it's a driver or OBS fault. Overall WDM driver compatability with software isn't particulary good.