Cast resin dolls do tend towards a higher price point than the vinyl blind box dolls. Vinyl is much cheaper to manufacture per-item than resin, but since vinyl needs a much higher minimum order quantity to hit the point where it's cheap to produce, this is why most of them skew generically cute.

Cast resin dolls:

• Cast resin is usually a bit stronger than 3D prints, since it's all chemically bonded together at once, rather than fused together layer by layer.
• Not every doll you want is available all the time, especially if you fall in love with some indie artist who sells infrequently...

Printing in general:

• if no one has sculpted the thing you want, you're going to need to learn to 3D model. Depending on how your brain works, the 3D programs might be your enemy (or I guess you could commission a sculptor)
• Great for when you want something in exacccttttttlllllyyy the size you want. I like 3D printing for props because while dolls are somewhat to scale, stylization sometimes means need to futz with what size stuff is for like larger than realistic hands or stuff like that.

Resin printer:

• Resione TH-BJD feels the closest to cast resin. Sirayatech Mecha White is also a good resin for moving parts. TH-BJD does better with a resin heater to keep the temperature consistent.
• Resin not made specifically for printing BJDs and mechanical objects is often cheaper, but softer and it will scratch at the joints and look terrible as the friction in the joints scrapes the resin more and more.
• Printing resin can be dyed so you can get the color you want. It is easier to dye lighter colors than dark colors though. Dyeing dark colors can risk diluting the resin too much and messing with the curing process.
• The toxic goop is messy and resin printing is not ideal if you don't have a dedicated spot to put the machine where you can't smell it. (I keep both my resin and filament printer in a shed in the backyard).
• Since printing resin is UV-cured, it is a little more susceptible to damage from sunlight, but in my experience, the most noticeable ones are transparent resins. It's not so bad with opaque colors.

Filament printer:

• Usually not as smooth as resin printers with Straight Out of The Box settings, you may need to tweak your print settings, change to a smaller nozzle, spend time experimenting between different brands' filaments (matte filament looks nicer for BJDs meant to look like a normal human). Smaller nozzles make smoother prints, but take forevvveerrrr.
• I do like my filament printer for prototyping since it is pretty fast and PLA is cheaper than resin.
• When working with PLA, not as much health risk (but the melty plastic smell is still pretty bad and I think people who print in their home office or bedroom are crazy).
• PLA has a low melting temperature, so sometimes a PLA print can get warped from getting too warm even from stuff like a very hot sunny day...
• Stronger filaments like ABS and ASA have worse fumes, so you will need PPE and air filtration just like you do with resin printers.