What is the best super 8 camera? Well of course the one you have with you! No kidding, it's all about what you do with it and want to film. There are some very good high-end cameras, a lot of decent cameras, and a whole bunch that might be better avoided. I say, definitely avoid the Nizo Integral cameras, I never had a single one that actually worked. I recommend a Nizo 481, 561 and 801 if you have a modest budget and you don't need to record sound with an external recorder.
First of all: what do you want to do with your camera, film indoors or mainly outdoors? Sport events, fast camera work or will it be on a tripod a lot? Most cameras will shoot at multiple speeds but the cheaper ones tend to only have the 18 fps. option. At this speed, your precious film cartridge with 50 ft. (15 mt.) of film will last around 3 min. and 20 sec. Also good in low-light conditions since the slower shutter speed will let more light through. Most sound cameras have 24 fps. which means you can film approx. 2 min. and 30 sec. with one cartridge.
In the good ol days Kodak and other film manufacturers like Agfa made sound-striped super-8 cartridges. These only fit in sound cameras, like the 1014XL-S, 814XL-S or some Nizo's. Unfortunately these films are not made anymore. If you want to record local sound, use a (digital) recorder for editing in post-production. Be aware that cameras which were not intended to record sound, can be more noisy, so buy a Nizo 2056, 4080 or 6080 or 1014XL-S or 814XL-S or any other super-8 sound camera, which are more quiet if you want to record sound.
I really recommend processing your own film, it's incredible rewarding. It's not that difficult and all you need are some chemicals and a super-8mm developing tank.
What's your Super 8 worth? Take a look at this list of Super 8: sold cameras for a value indication.