I've got a friend who does a lot of YouTube videos. What he finds is that when the camera is on a tripod and he's self-recording video, the focus system is the biggest issue. He has to focus and make sure he remains at a consist distance from the camera (a bit of a challenge.) This is because most DSLR cameras cannot do continuous auto-focus during video (or if they do, they don't do a very good job.)
This is because the impressively fast focus system on most DSLRs is based on using "phase detect" AF sensors which are on the floor of the camera (not on the sensor.) The reflex mirror has to bounce light into that sensor -- but when shooting video (or liveview) the mirror swings clear of the image path ... no phase-detect AF. This leaves the camera with "contrast detect" AF (which it can do on the sensor) but this involves focus-hunting and is slow (during video you visibly see the camera trying to guess it's way to sharper focus and this is very distracting.)
Years ago Canon started developing a technology to solve this. It uses micro-prism on the sensor to create what they call a "dual pixel AF" system directly on the sensor surface. You get the capabilities of phase-detect AF even when shooting live-view or movie mode.
Some of the G series (advanced point & shoot models) were the first to get this. The Canon EOS Rebel SL1 got an improved version. But more recently the Canon 70D, then the 7D II, and then ultimately even the T6i have this new system.
The SL1 has a 2nd generation version of this focus system. The 70D, 7D II, and T6i have an even more evolved system. But considering most cameras have nothing at all... this is a huge advantage for shooting video.
When shooting your own YouTube videos, you have the luxury of controlling many factors... including lighting. ISO and DR won't be a problem (or shouldn't be -- if they do, you have to blame yourself.)
I think that for your particular purposes, the auto-focus system during video will be a huge factor. Next in line is the lenses -- and Canon has the advantage in that department too. Canon now offers a number of lenses with their "STM" focus motors. These motors are EXTREMELY quiet. They developed for video because cameras (particularly when using the built-in microphone) could hear the noise of the focus motor. The STM lenses make almost no noise at all (some lenses can't be heard at all... some lenses can be heard but you really have to struggle to hear the focus motor.) Another nice advantage of these lenses with the new STM focus motors is the optics. These are consumer-grade lenses and, as such, the optics usually don't compete with the higher end lenses that cost considerably more. Canon redesigned the optics when they upgraded their standard consumer lenses to the STM version of the lenses and the optics got a big upgrade.
One last factor is that when you buy an entry level Nikon (like a D3300) the camera relies on the lens to bring it's own auto-focus motor to the party. Higher end Nikon bodies have a motor built into the body OR can use lenses that have their own focus motors. On the Canon side, the focus motor has always only been in the lens. This means all Canon EF lenses will autofocus on all Canon EOS bodies. But on the Nikon side quite a number of their AF lenses can only auto-focus if they are on a Nikon body that has it's own autofocus motor (and if you're like most YouTube'rs then you record your videos solo (no camera operator) and that means you MUST have auto-focusing lenses. This changes things because the Nikon AF-S lenses that have their own focus motors cost more than the AF lenses that rely on in-body motors. Canon has a "nifty fifty" (50mm f/1.8 lens) that costs about $100. Nikon has a fairly inexpensive 50mm f/1.8 lens too... but it requires the body have it's own focus motors (the D3300 does not). Nikon does have a 50mm that can auto-focus with the D3300 body -- but it costs about twice as much. If affordability of the camera system is a factor, the price and quality of lenses you might realistically want to use becomes a factor.
This is not to disparage Nikon gear. Nikon makes a LOT of VERY impressive gear and I believe that ultimately the skill of the person holding the camera is a more important factor. But given your specific desire to use a DSLR for YouTube video recording AND not wanting to buy a dedicated video camera (because that ultimately would be better) because you still want to be able to shoot good stills -- and given your price/budget constraints (which limits you to entry-level bodies) -- the SL1 is probably your best bet.
If money weren't an issue I could think of a lot of cameras I'd rather use -- but unfortunately money usually is an issue.
