speed doesn't necessarily = bad quality.

Different printer designs will cope better at different speeds.
I've recently had some pretty good prints from my he3d k200 delta at 200mm/s.
The fastest I run my makerbot clones is about 65mm/s

However speed is dependant on a lot of different things. But generally speaking deltas can and do print faster than the other types of 3d printers.

Had my regular look at ebay last night.
a delta lit with heated bed and supposedly 'intelligent' autolevelling can now be had for ?125 !
And a basic i3 clone kit - also with heated bed - for ?88.
Both shipped from the uk (no import tax) and with free postage !

If had a larger workshop I'd probably get one of the i3's to play with.
Currently I have nowhere for it to live - but damn !
In another couple of years they will be giving these things away with cornflakes.

so pretty much the only thing currently important for buying a 3d printer is your budget.
The ?88 i3s are NOT equal to something like a mk3 genuine prusa i3.
Or a creality cr10 kit which is around the ?250 mark.

It's not strictly accurate to say you get what you pay for - ultimakers, for example, are massively overpriced.
But a better budget will = a better printer.

Plus given how many differenmt makes and modelas and types of machine there are - knowing your budget means we don't spend time on machines you can't afford. :-)