I would recommand a corexy or a delta. I'm not expert of deltas, I know there are some good.
Some good corexy builds are for example : hypercube like tbowmo said, d-bot and voron..
Mine is a corexy I built myself from different designs I saw.
I understand that people doesn't want to invest much money, or think a better build costs more (not true), and they want it quick to assemble with decent quality. Wow that's a lot of requirements for something cheap
Imho, I choosed to build it myself because I wanted to know every detail. If I have a problem, I know what happens, and not stuck
Some important details (personal view)
- using aluminium, like vslots. I'm also of those who think it's too bad to use plastic corners for an aluminium structure. better use aluminium corners
- check the build&reviews of the printbed (for corexy) if there is any cantilever problem.
- Strong rods (8mm diam is too cheap..).
- bearings; not the cheapest.. else you can get imprecision in long term, noise etc. (vwheel when you can, and you build it yourself are nice too)
These points will help a lot the machine to keep its calibration longer, print fast, without wobbling, so a better print.
I think, a cnc in general, you can ask people working in this field, always need to check the calibration or recalibrate time2time for a good job. so what expect of a dirty cheap cnc..
This is a special process, control melting temperature, different speed parameters, push&pull filaments to prevent oozing, bed leveling because if first layers are not good then it won't be great etc..there is some learning curve, that no matter you buy a cheap or exepnsive machine, you'll need it.
Finally a few points that are good to consider:
- not too small print area, or may be disappointed in future when you want to print bigger
- heatbed is very useful
- autobed leveling is handy
- i like cube structure, it's easier to enclose if you want to use different filaments.
- and if enclosed, using hot temperature for a print, check that critical assembly parts have not been printed with PLA if you bought a kit, as they could soften a very little bit, and lose accuracy during print.
I'm sure i forget lot of interesting details. It's not very complicated to understand how it works, just needs to read and test. very interesting. then you'll have your mini routines for each tasks.
I hope this helps.