Now, while Enjin might be the easiest forum software to use, please hear me out on this. Enjin, while easy to use, gives off an incredibly unprofessional and generic look and feel to the forums, is incredibly limited as to what you can actually do with the forums, is incredibly expensive for what it offers (virtually nothing other than their generic forum software and half decent but overpriced web hosting) if you don't want ads shoved in the face of your community, attempts to shove its branding wherever it possibly can, is absolutely filled to the brim with spambots (forums running on other software are as well but not to the same degree and it is usually easier to combat on other forum software) and, while it is easy to use for admins of the website, I find it to be incredibly complicated for users. XenForo is probably the most feature packed of all forum software, but is pretty expensive, sitting at 140 dollars for a license (if you do get a constant stream of donations like I would assume you do, this really shouldn't be so much of your monthly donation totals that you can't pay off existing server bills). However, after the initial purchase of the license, it won't add much onto your existing bills for this website, since most half decent web hosts are around a dollar or so cheaper than Enjin Advanced is monthly. If you really don't want to pay 140 dollars for a license, then there's also pretty good free forum software as well (SMF and MyBB come to mind). Installation might not be as easy as it is with Enjin, but with a little tinkering around you should be able to figure it out. tl;dr: enjin is suck and literally anything else would look more professional for a decently sized Minecraft server getting what I assume to be a decently large stream of donations I'm not sure how much you guys pay for Minecraft hosting but getting a dedicated server (from, for example, OVH) and just running everything off of there might be more cost effective as a whole for both the server and forums if you rent one of the ripoff plans from, for example, Beastnode or MCPH.
I'm most familiar with running phpBB myself. I've always had good luck with that myself and am very familiar with the backend code.
I agree xenfro looks much more professional, is much easier to navigate and from past experience is very easy to moderate. I'm all for it.