Steadytech from Box is a good basic PLA filament at £20 a roll.
If you want something a bit nicer then
Fillamentum do some great plain PLA, and some amazing metallics. Rapunzel Silver is one of my favourites.
Proto Pasta HTPLA is fantastic stuff, also in plain or metallic. This can also be annealed in the oven to increase strength.
For real wow-factor,
Polyalchemy Elixir is very special.
Ziro make a rather nice marble-effect filament too.
3D Filaprint are my go-to supplier for filaments. They do Fillamentum, Protopasta, and Polyalchemy, plus many more. They also do an own-brand of cheap PLA but personally I don't rate it much as it's a pain to get it to adhere to the bed. I prefer Steadytech for basic printing. They're great for all the others though. They also have a
Filament Sample Outlet which is really handy for getting filaments to play with, without having to buy a full spool.
I've found that the CR-10S can really only print PLA well because of it's PTFE hot-end which can only go to 240 degrees. PETG will print at 230, but not well. ABS will print, but warps and falls off the bed because it won't go hot enough. TPU just won't print at all with the bowden extruder.
I'm contemplating upgrading the CR-10 to an all-metal hotend like the Microswiss, but I'm going to build a Hypercube with an E3D V6 hotend which will overcome a lot of the limitations so I may leave the CR-10 as it is. TBC
