Personally, and I openly admit to 25+ years of bias, I would select a Mac. For tasks like video editing, photo editing, music editing and combining any or all media into a project a Mac is the de facto standard in a lot of professional set ups.
If portability is important and if funds are up to the onslaught, a MacBook Pro; forget about a MacBook Air for any kind of serious video editing.
MacBook Pro & pre-installed software
If portability is not important then an iMac has the advantage over the portable range in display real estate out oif the box and usually offers more options for expanadibility.
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If you want a budget "design and build your own" then, my current "desktop" of choice is that incredible little brick the MacMini. Bear in mind when making a purchasing decision that you must add your own keyboard & mouse, display etc to the base system here.
MacMini
For me the choice would be clearly between the iMacs and whatever additional software is deemed necessary to achieve the owner tasks easily. This to me is where Apple and the Mac OS score over every other hardware / software combination every time - ease of use and consistency, the true power of everyday computing.
All of the systems I have listed have sufficient built-in software to hit the ground running with a minimal learning curve for the novice film-maker / editor. As soon as the built-in tools begin to lag behind the power and ingenuity of the user, then there's the option of installing professional grade software (also from Apple) to close the gap, with the assurance that the earlier learning & acquired skill-set can be applied to the new but very familiar set-up.
N.B. Apple also offers decent educational discounts - check with their pre-sales / sales telephone support numbers listed on the web-site.
HTH