The CR10 has a bowden extruder - you can see it mounted on the left side of the frame connected to the hot end with a length of teflon tube.
Nice thing about bowden extruders is they mean less weight on the gantry so potentially higher accelerations and therefore print speeds.
But...they can also be trickier to get working well since you have so much filament between the drive gear and the nozzle and that length of plastic acts like a spring. With normal filaments that usually just means a bit more stringing/ooze to deal with and isn't a huge deal. But with softer filaments like Nylon/PETG and especially flexibles can be really tricky.
On my Folger 2020 i3 I use this extruder with a genuine e3d v6 all metal hot end:
https://www.thingiverse.com/thing:825133
It's listed as a folger extruder but would work on any Prusa derived machine...could probably work on the CR10 as well - though I worry about how the CR10 would do with extra weight moving around given how little support there is in it's structure.
I added two of my own modifications to that extruder, first I tweaked the idler so it's easier to release for changing filament:
https://www.thingiverse.com/thing:1427181
Then I added a mount for my inductive sensor:
https://www.thingiverse.com/thing:1428292 And later modified that to also include a mount for a cooling fan along with the sensor:
https://www.thingiverse.com/thing:1449709
I'm not 100% happy with this extruder - but it has handled flexible materials just fine since the filament is fully constrained as soon as it leaves the drive gear. Well, it can be. If you look closely at the photos on those mods I did you'll see the teflon tube ends just under the gear...I since swapped it for a very slightly longer one cut into an upside down V so it fits right up there.
My big complaint about this extruder is the idler. I don't get as consistent results as I did with the all metal mk8 I had swapped my original fogler supplied extruder for. The mk8 worked better than the stock plastic because I was able to adjust the tension on the idler (The stock extruder it wasn't adjustable) and I found that increased tension really gave me great prints. This one does better than the stock folger one did but still not quite as good as the metal one - but there's no way to mate an e3d v6 to the metal one short of going bowden and I didn't want to mess with that.
I really want to swap to a geared extruder so it will go easier on my extruder motor (which runs hotter than any other stepper on my machine) and hopefully with a better idler so I can give more tension. But...I've yet to find or design a geared extruder that will allow me to mount a cooling fan and my inductive sensor.
I almost got an e3d titan a week or two ago when filastruder had a big sale with some $50 off discounts. They only had a limited number of discounts though and while I was quick enough to get one when I started my checkout by the time my payment cleared they'd all been used and I got charged full rate and had to cancel the order
But it's on my Christmas list so we'll see if my wife surprised me