Why don't you just wait until you're a student, then sign up for both (since they are free to students)? Then you can decide what value they offer.
After seeing your post, I glanced at VetCompanion (had not heard of it prior to that).
Can't say I'm impressed after a cursory glance at their website ... but I also haven't used their service. Two things jumped out at me on their info page:
"
- Unlike online veterinary message boards, which are prone to bias and personal opinion, or quick reference textbooks, which are quickly out of date, VetCompanion allows instant access to information that is concise, current, well written, and easily accessible on a smartphone, tablet, or computer."
Seems like a pretty clear shot at VIN ... which is fine, because VIN has a lot of negatives and as much as I use it I can't say I love it. I personally use VIN for looking up recommended therapy for cases similar to whatever I'm struggling with. I also use its sister site veterinarypartner.com for printing out client education sheets for certain problems that I routinely see.
I HATE the way VIN looks, and its forum software is just ... awful. It's like retro 80s but worse. VIN insists that you'll grow to love it, but no matter how many times I try - it's awful, plain and simple. The other thing I don't like about VIN is the attitudes - there are a lot of people who seem to spend their time on VIN purely for the purpose of jumping down their colleague's throats with some haughty know-it-all attitude.
But if you sift through that, you can find expert (boarded, anyway) recommendations on just about anything. If you want, you can post a case and get an expert opinion - you just have to weed out the crappy responses.
And I'm not impressed by the "prone to bias and personal opinion" comment. EVERYTHING in medicine is prone to bias and personal opinion - if only by what pieces you choose to include vs exclude. I feel like that website is trying awfully hard to insist on how unbiased they are - which just makes me dubious.
"
- Includes full formulary access: Saunders Handbook of Veterinary Drugs: Small and Large Animal, 4th ed., by clinical pharmacologist and veterinarian Mark Papich, DVM, MS, DACVCP (Copyright 2015 Elsevier Inc. All Rights Reserved)."
Meh. So what. Personally, I've never even used that formulary. VIN offers at least a half a dozen formularies, including Plumbs, BSAVA, and others. Not impressed by pushing Saunders.