If I have size 10 feet, should i get M or...
If I have size 10 feet, should i get M or L
Its up to you, the medium will go up to a 11 so you are good there and the binding will be slightly smaller. If you are still growing or your bigger footed buddies will want to ride your board get the Large.
Chris Jones is right! I'd stay with a medium as you don't really want any play in your binding/boot setup. The only reason you may want a large would be if your boots are old-school and boxey... then it may be a bit of a tighter squeeze.
I hate it when bindings are on the small side. It sucks when you have more toe off the board than heel. Also, you want the footbed to reach all the way out to your toe so you have good responsiveness. I wear 10.5 boots and always ride large binders. I have some M/L Rides and I wish they were bigger.
I am size 10 boot and demo'd L, bought M, am now returning M for L. Boots are 32, Level 2, only a couple years old, so probably wouldn't be considered big and boxy. Anyway, I could not get the M to fit right. I was near the tightest settings on the L, which is why I wanted to try an M next. But the L fit just how it should. I think triad performs better if it is on the larger rather than smaller size, which is kind of counter-intuitive, but I think it has to do with geometry and kinesiology.
JD and Wakozachos answers seem to be a little closer to the truth regarding rocking boots that are borderline of the binding manufacturers sizing suggestion, especially when it comes to the Triad. I bolted these badasses (last years model) to my Burton Custom wide 59 last year and this years model to this years Custom Wide 62. Having ridden wide sticks since the inception of the Floater, I have worn boots from size 12 to 10.5, depending on the brand. Currently, I am sporting 10.5 Salomon Synapse (last year I wore the Salomon F22, also a 10.5). Both pairs of Triads were large and as the boots packed in, I was able to adjust the binders to maintain complete tightness thanks to Burtons straps having tremendous adjustability. I inserted the new boots into the medium Triad in a local shop and even with the gas pedal fully extended, the toe of the boot hung over the edge of the almost an inch and a half. Go with the large, you will not regret it. Oh yes, the heel of my 10.5s did NOT shift or wiggle in the heel cup of the large.
I have a pair of size 10 Hails and they fit the medium Triad perfectly. Go for the medium if possible as it'll allow you to ride a wider range of board widths.