There's too many cameras to say what is "best". Polaroid made hundreds of cameras while they were active and Fuji have a huge line of Instax cameras across three formats (Mini, Square and Wide in order of size of print).
I prefer the Polaroid emulsion and colours. But their film is 2x the price of Instax film and takes twice as long to develop. Also it must be stored correctly, if it's left in a hot warehouse the film can be ruined. Instax hasn't got that problem. I've not had a ruined film pack (yet) thank god. For me the Polaroid colours are worth the cost.
Lomography's instant cameras take Instax, yeah. There are also companies like Mint making premium instant cameras. They just released a full on premium rangefinder called the Mint RF70 that takes instax wide film (pic related). It looks awesome but I can't afford it or justify it.
If you want to dabble in instant film grab a cheap Polaroid 600 camera off eBay and some 600 film. Or a Fuji Instax Wide 300/Lomo Instant'Wide, they're both about the same except the Wide 300 you can't turn off the flash. Or if you're feeling fancy grab an old Polaroid SX-70, it's a folding manual SLR. See >>3558499
. The SX-70 is what Andy Warhol and Ansel Adams were famous for using. It has a lot of cool history if that's what you're into.