Full disclosure, I purchased a Vagabond and I have had their first model on my truck for 3 weeks (as a loaner). I paid full price for mine, and they have not asked me to write this or given me any feedback on it - nor is this sanctioned by them. 100% my own opinion.
With the recent price increase for the GFC to $5750 I don't think there's any reason to get it over the Vagabond. I'm sure some people will take offense to that, and that's fine. Lots of peoples identities seemed to be wrapped up in what camper they paid a lot of money for. We can all have our opinions, and ultimately I can say if the GFC came to market 6 months ago I would have happily paid their asking price and been thrilled with it. It's a giant leap forward from anything else on the market previously. I've stated before that I think the coolest part about both of these coming to market is seeing how people build theres out - hopefully Habitat, GFC and Vagabond owners can all come together on this and sing kumbayah and build dope glamping setups.
That being said I think the GFC is more of a RTT on a shell while the Vagabond is a true camper, so one isn't necessarily going to work better for everyone.
I think there are two downsides to the Vagabond over the GFC:
Weight - 100ish lbs difference between the two. Once you start loading it up I think that number will be pretty negligible - an ARB fridge weighs more than 50 lbs, my dog weighs 60, 12 gallons of water weighs 100ish, etc.
Price - $750 more, but I think it's a better value.
Extrusion on side of GFC - neat to attach accessories easily, but you can just drill in the Vagabond which I plan on doing. But then you have a hole.
The biggest problems I see with the GFC:
Side tent windows - They are too small, and their placement towards the cab (where your feet will be) is truly odd. Additionally, the Vagabond uses a three layer window (mesh, clear vinyl, tent material) which is awesome and offers a lot more flexibility.
Transform-a-floor - I think the theory behind it is cool, but I think it's needlessly complicated. In their video they show the "full bed" configuration where the pillows are all stashed over the cab and makes the space unusable. I don't think the Vagabond marketing has properly illustrated how they do their floor, but it's essentially two panels that can slide under eachother. The mattress is two mattresses that are velcrod together that creates a hinge and allows them to be folded over on top of eachother. In this configuration there is still enough room to have a fully open bed, yet still be able to put a dog there and other items while you work in the bed. I have done this several times in inclement weather and it's absolutely clutch. The other key point is that it does not look like you will be able to sleep two reasonably sized adults side by side and still have access to the bed - which you can do easily with the Vagabond.
Exposed struts - seems like they are in danger of getting ripped off or damaged in tight trails (like those in Western WA). I will say that being attached to the extrusion makes replacing them easy I bet.
Translucent ceiling - I've heard a ton of reasons for this and none of them make any sense. If I want light in the camper I will create it, otherwise I don't want to be woken up by the sun - if I did I would set an alarm or open my windows. One of the things I loved about my Alu-Cab was how dark it got inside when you wanted it too.
No rear window as standard
Water sealing - it doesn't look like the front of the camper (near the cab) has done anything to seal up the gaps in the Tacoma bed. Speaking from experience with other metal camper shells (Alu-Cab) you need to do something about those gaps or a surprising amount of water will get in. I've seen reports from people who live in SoCal about how waterproof it is...lol.
Advantages of the Vagabond:
Simple, more effective floor/sleeping area that is also larger and more flexible - you can sleep two adults side by side, yet still get in/out of camper or work on a laptop below.
Integrated electronics features - the Vagabond interior has ways to (by design) route power cables throughout while keeping them secure (through special zip ties) and hidden. Very cool! Additionally, they have panels you can purchase that you can attach light switches, fuse boxes, etc. to in a way that makes it clean and like it came from the factory like that.
Large side windows that are positioned so you can see out of them
Triple layered side windows - No window, mesh, clear vinyl, tent material (privacy screen) offer more flexibility. The clear vinyl is really nice and allows you to still see outside and take advantage of natural light during a rain storm.
Larger sleeping/living area - you can have two adults sleeping side by side and still work on a computer below.
Lockable tent area - side doors will lock on the GFC but not being able to lock the actual tent seems like an interesting oversight.
Large rear window comes standard - seriously, this window is gigantic AND it comes already tinted. Additionally the cab-facing window flips down for ease of cleaning or sticking long objects through the cab.
Waterproofing - the Vagabond comes standard with a weather sealing strip that goes over the bed where it meets the cab (where there are giant holes in the Tacoma bed) while my Alu-Cab did not and leaked profusely through there. Additionally, the tent material is some maritime vinyl material that is 1000% waterproof and is awesome. I have driven through several major rain storms, and camped in the rain and not a drop of water has gotten inside. As a side note, I've ruined a CVT tent because the nylon got wet and moldy - I'm not saying it wouldn't happen with this but the material is absolutely more resistant to that and is in fact waterproof.
They made the original wedge camper for Tacomas - I'm not saying the GFC is a copy of it the Vagabond, but the Vagabond guys made the first one and I like to support small businesses whenever possible.
I'm sure I've forgotten some stuff but would rather put this out now than stew on it for a week to add another line.
Flame away