Have been reading all kinds of info and frankily I am wy confused!

I am on 3.40 oe-a and ws considering upgradig to 3.52 M33-4 or 3.71 M33.

Which is better and can anyone recomend where I can DL a safe upgrader and also let me know if I have to go via any firmwares to get to the destination (eg 3.40 to 3.52 to 3.71?) or can I upgrade to the particular version directly?:rofl: