Nothing really is the best, but I think Funosr(store from Aliexpress)'s OSR2 is affordable and pretty easy to begin.
Best to really look into each device and find out what one appears best in your eyes depending on what you are wanting out of them and what gives you the most pleasure while at a cost you can manage or disadvantages that come with each device.
My opinion/view
If you want the most ways to gain pleasure with no regard for your accountant nor mind a noisy machine then SR6 is the one for that due to it’s multiple axis allowing pretty much omni-directional movement.
OSR2/OSR2 are step downs from the SR6 and thus are more cheaper but if you find it slightly lacking you can easily use most of the parts for an SR6 build.
Those however require yourself (or an friend) to be okay with the idea of DIY’ing repairs/fixes if a servo gives out or something breaks which can save you a lot of money in also gaining one since making it yourself can save you maybe more than half the cost of getting it pre-built. (depending on parts you get and price for them) But that can also mean that you can have different servos or parts to reduce the noise or solve anything that you believe is an issue or want changed. e.g. change the plastic arms out for stronger metal variants.
Syncbot from what I understand is like more like the Handy with some multi-axis stuff but it is more or less just suction/sequeeze axis than any side to side movement. Additionally it requires a specific script for it to work as it wants it all in one rather than multiple script files. Finally you may find problems with it hard to rectify since there are a few topics on here that have complained about it’s durability and customer service. (Though when it first released it was highly praised so could be just people hating)
Just about ready for SR6. It seems like multiaxis scripts are lacking, or maybe just more difficult to find. Any talent in that area is very much appreciated
Id love someone to break down how to script on a controller for the roll/pitch.