A 12V fridge is one of the best quality-of-life upgrades you can add to a van. Being able to buy fresh produce, meat, and dairy and know it'll keep for a week or more is genuinely liberating. The expensive brand names (Dometic, ARB) run $800-1,500+, but the technology isn't exactly space-age - cheaper alternatives in the $200-500 range work well and have gotten quite reliable.
In my experience, the three things that matter most when choosing a fridge are: single zone vs dual zone, overall capacity, and whether it physically fits the space you have. I've designed both of my builds around the fridge I intended to use - measure the space first and find a fridge that fits, rather than building out your interior and hoping you'll find something that works.
Single zone fridges have one compartment - set it as a fridge or a freezer, but not both. Dual zone units have two independently controlled compartments, so you can keep one side as a fridge and the other as a freezer. Dual zone typically costs $100-200 more and the zones are usually split 60/40 or 70/30.
If you're mostly doing weekend trips, single zone is fine. If you're living in the van full-time or taking longer trips, having a freezer section for meat, ice, and frozen meals is really nice. Another benefit of dual zone: if you're storing less food and want to conserve power, you can just turn off one side and run the other.
Get bigger than you think you need. Running a half-full 50L fridge is way easier than playing Tetris with a 30L one, and the power consumption difference is minimal. A 40-50L unit is the sweet spot for most van builds.
Top-opening (cooler style) is more energy efficient since cold air stays in when you open it, and they tend to fit into more places. Front-opening is easier to organize and can slide under a counter. For most van layouts, top-opening makes more sense unless your build specifically calls for a front-opener.
Don't underestimate this. Know your fridge dimensions before you finalize your interior layout. I've seen people finish their build and then discover they can't find a fridge that fits the gap they left. Measure the space, find the fridge, then build around it.
Most 12V fridges draw about 30-50 watts when the compressor is running, but the compressor only runs 30-50% of the time once cooled down. Over 24 hours, expect roughly 20-35 amp-hours depending on ambient temperature and how often you open it.
That's very manageable - a 200Ah battery and 200W of solar can easily support a fridge plus other basic needs. Don't let power consumption scare you away from getting one.
A good cooler with ice ($100-300 for something like a Yeti or RTIC) works fine for weekend trips - 3-5 days of ice retention is plenty. No electricity needed, no installation, and you can take it out of the van and use it anywhere.
But it gets old fast if you're using your van regularly. Buying ice, dealing with wet food, draining meltwater, losing capacity to ice - it's just ongoing hassle. If you're building a van you'll use more than a few weekends a year, I'd budget for a 12V fridge early on. Treat a cooler as a temporary solution until you can upgrade.
I found a great deal on a lightly used Dometic for my build, but I don't think the brand-name premium is really justified here. The underlying compressor technology is the same across brands, and the Chinese manufacturers have gotten good at building reliable units. If I hadn't found such a good used price, I'd have gone with something like the Vevor dual-zone below or a similar off-brand option.
I haven't personally used this specific unit, but Vevor's 50L dual-zone compressor fridge hits the sweet spot for most van builds - good capacity, independent fridge and freezer zones, and a fraction of the price of a Dometic or ARB. If I were buying new today, I'd be looking at this or something very similar.
Link to the Vevor dual-zone fridge →Bottom line
Get a 12V fridge if your budget allows. Go with a 40-50L top-opening unit, get dual zone if you want a freezer, and measure your space before you buy. You don't need to spend $800-1,500 on a Dometic - a budget option in the $200-500 range will serve you well.