All of the above are basically the same---support the artist monthly and get exclusive bonuses.
Let's talk all three of them and discuss which is the better one.
Updated by JAKXXX3
Topic: Patreon VS Enty VS Pixivfanbox
Posted under Off Topic
The pragmatic answer is that the platform with the artists you care about is going to be best.
Also, I believe there's subscribestar but I'm unsure to what extent they support digital artists.
Updated by anonymous
Pixivfanbox sounds like a Japanese one, seeing as Pixiv itself is primarily Japanese artists. Patreon's the only one of the three that I'm actually any familiar with, though not by much even then.
Updated by anonymous
There's also Ko-fi Gold and commiss.io. Though commiss.io seems to be more about managing commissions and having a tip jar, rather than being a monthly support thing.
Updated by anonymous