A larger effector is a bit more stable I have found but you may lose some print size. The Kossel mini effector is about as small as I would consider.
I prefer my extruder mounted on top, pointing horizontal. I did my Rostock in the middle pointing up, so the bowden made a "U" shape and it always flopped all over. I also trid center mounting horizontal, that didn't work well either. Mounted at the top, horizontally, it seems to behave more, it's also shorter. In all cases, at the end of the day, put your effector down, this will keep your tube from taking a memory shape that lends itself to flopping.
My thoughts on the extruders I've used (Don't go cheap! Just like a cheap print head, extruders will cause you a lot of headaches!)
Ez Struder - LOVE IT! However, I don't recomend it for anything much smaller than a .5mm nozzle, as it lacks the torque for it, even with a Kysan. If you are using a large diameter nozzle though, this is the best extruder in my experience. It's simple, cheap and effective. Don't be fooled, nozzle size is far less important for quality than layer height.
Airtripper - It works well, but it's overcomplicated and again, lacks torque for smaller nozzles.
Berry Tripper- (Gregg's and Richrap's are all similar) One of my favorites. However, if your herringbone gears are not perfect, it can destroy itself (body and bearings). Use straight cut gears and it will be easier to print and last longer. This could push your finger through a bowden tube it has so much torque. In fact, due to some oversize fillament, I broke several pneumatic fittings with mine. Like the Air Tripper, it's a bit over complicated, bulky, and the gears, while handy for feeding filament manually, can nip your fingers if you aren't careful. I don't know how much damage it could do if it ever caught your finger fully into the hears, but it would certainly not be pleasant. This was always my go to extruder for my Rostock and if I didn't have the geared Nema, the Greg's or Richrap would probably be my choice today (it's more compact and has quick release compared to the Berry). If you use one of these, print the pinion from ABS and the spur from PLA. This quiets it due to dissimilar materials, but also ensures your pinion doesn't stretch and deform as easy. However, I would still do any of them with straight gears. If you want to use a standard Nema 17, use one of these, the Ultibots 1.75mm hobbed pulley, and use straight cut gears, it will work great. The YRUDS would be great if it had quick release.
Various PG35L extruders - I hated this setup. The motor really needs a heat sink for smaller nozzles. It also is gear reduced so much that it will not only slow your print speeds, but I couldn't eleiminate blobs due to the slow retraction. Basically, I just a bad experience with this. Warning, the gear box on this REQUIRES output shaft support. The output shaft only has a single bearing supporting it and many extruder designs don't do this. It will tear itself apart quickly. I also don't like the idea of an effector mounted extruder, bowdens are an inconvenience, but weight really slows a delta. My small Griffin usually runs at 200-350mm per second (depending on the job), and there's no way this could keep up, nor could the printer move that fast with it mounted on the effector. This goes double if I used magnetic joints.
Johann's Extruder and variants - A bit costly, and you need the 5:1 version, which is still a bit overgeared (retraction is a bit slow), but otherwise, this is the most elegant and best working sollution I've seen. If they made a 2:1 or 3:1 version, it would be perfect. I broke a fitting (and bowden tube) with this setup as well, and in a more spectacular fashion. The one big downside (besides price) is a lack of hobbed pulleys, no one makes a 1.75mm version and most 3mm hobbs don't work so well on ABS. With the torque of these setups, there is a fine line between slipping or ovalizing ABS, which jams in the bowden.
Personally, I'm using two Griffin Extruders, which are similar to the Kossel extruder, but works with a Nema 17 or Geared Nema. l use it geared.
I prefer my extruder mounted on top, pointing horizontal. I did my Rostock in the middle pointing up, so the bowden made a "U" shape and it always flopped all over. I also trid center mounting horizontal, that didn't work well either. Mounted at the top, horizontally, it seems to behave more, it's also shorter. In all cases, at the end of the day, put your effector down, this will keep your tube from taking a memory shape that lends itself to flopping.
My thoughts on the extruders I've used (Don't go cheap! Just like a cheap print head, extruders will cause you a lot of headaches!)
Ez Struder - LOVE IT! However, I don't recomend it for anything much smaller than a .5mm nozzle, as it lacks the torque for it, even with a Kysan. If you are using a large diameter nozzle though, this is the best extruder in my experience. It's simple, cheap and effective. Don't be fooled, nozzle size is far less important for quality than layer height.
Airtripper - It works well, but it's overcomplicated and again, lacks torque for smaller nozzles.
Berry Tripper- (Gregg's and Richrap's are all similar) One of my favorites. However, if your herringbone gears are not perfect, it can destroy itself (body and bearings). Use straight cut gears and it will be easier to print and last longer. This could push your finger through a bowden tube it has so much torque. In fact, due to some oversize fillament, I broke several pneumatic fittings with mine. Like the Air Tripper, it's a bit over complicated, bulky, and the gears, while handy for feeding filament manually, can nip your fingers if you aren't careful. I don't know how much damage it could do if it ever caught your finger fully into the hears, but it would certainly not be pleasant. This was always my go to extruder for my Rostock and if I didn't have the geared Nema, the Greg's or Richrap would probably be my choice today (it's more compact and has quick release compared to the Berry). If you use one of these, print the pinion from ABS and the spur from PLA. This quiets it due to dissimilar materials, but also ensures your pinion doesn't stretch and deform as easy. However, I would still do any of them with straight gears. If you want to use a standard Nema 17, use one of these, the Ultibots 1.75mm hobbed pulley, and use straight cut gears, it will work great. The YRUDS would be great if it had quick release.
Various PG35L extruders - I hated this setup. The motor really needs a heat sink for smaller nozzles. It also is gear reduced so much that it will not only slow your print speeds, but I couldn't eleiminate blobs due to the slow retraction. Basically, I just a bad experience with this. Warning, the gear box on this REQUIRES output shaft support. The output shaft only has a single bearing supporting it and many extruder designs don't do this. It will tear itself apart quickly. I also don't like the idea of an effector mounted extruder, bowdens are an inconvenience, but weight really slows a delta. My small Griffin usually runs at 200-350mm per second (depending on the job), and there's no way this could keep up, nor could the printer move that fast with it mounted on the effector. This goes double if I used magnetic joints.
Johann's Extruder and variants - A bit costly, and you need the 5:1 version, which is still a bit overgeared (retraction is a bit slow), but otherwise, this is the most elegant and best working sollution I've seen. If they made a 2:1 or 3:1 version, it would be perfect. I broke a fitting (and bowden tube) with this setup as well, and in a more spectacular fashion. The one big downside (besides price) is a lack of hobbed pulleys, no one makes a 1.75mm version and most 3mm hobbs don't work so well on ABS. With the torque of these setups, there is a fine line between slipping or ovalizing ABS, which jams in the bowden.
Personally, I'm using two Griffin Extruders, which are similar to the Kossel extruder, but works with a Nema 17 or Geared Nema. l use it geared.