I'm new on streaming and would like to know what is the best capture card I will be streaming SNES and PS2 mostly if that changes anything Thanks
How much are you willing to spend on the capture card?
If you really want to maximise quality and money isn't an issue, go with an RGB capture setup. You'd need RGB cables, a SCART amplifier, Sync Strike and PEXHDCAP.
If you want decent quality, but also don't want to spend much, I'd recommend grabbing the EzCap 116, which captures composite (buy it from their website, to avoid fakes). Would not recommend going for the Dazzle, since that capture card requires bullshit setups to work.
To add to what Adam said, you can capture HD output from PS2 using Component http://en.wikipedia.org/wiki/Component_video which the PEXHDCAP can take as an input. As for SNES stuff I'm not too familiar with that.
I've been using the Elgato Video Capture (for composite capture from my NES, SNES & PS2) and it has been extremely simple to use and nice quality without spending a ton of money. Don't get this confused with the Game Capture HD, which is much more expensive and creates a few seconds of lag (which is awkward when you're splitting a few seconds ahead of the game).
I have an Elgato Game Capture HD and it's fine. I record my Sega Mega Drive, Wii-u and PS4 with it. I don't get any input lag either unless I'm looking at the preview window for some reason. But that's pretty much just to check that I have a good picture. There's no lag on my tv.
Having said all that, I do have to connect an upscaler to it for my Sega because the capture device doesn't have the correct ports for that console.
Yeah the Elgato game capture HD is pretty good for most things since you get adapters for pretty much everything. There's some latency (1-3 seconds) between your console to the computer though. It features a HDMI passthrough though with 0 latency. So if you have another monitor to play on, it's pretty good. But the video in OBS/Xsplit is gonna be a bit delayed. Not that it really matters in most cases.