Whatever ya got.
As stated earlier, its what you have. If you look at the posts in this thread you will see that most guys recommend sleds they owned or own. If you bought a 1M and rode it all the time and then jumped on a ZX for all of 10 minutes you would do far better on your 1M compared to that ZX because you have the 1M chassis traits patterned into your muscle memory. All will be good after you get used to them. If I HAD to say which one is best for sidehilling, for all ranges of riders (have not ridden a 1M before) I would say a ZX and this is coming from an EDGE owner. I find ZXs to be lighter and respond more to rider input versus the EDGE and I have enough time on a ZX to be comfortable and know the traits and the ZX have very advanced motors for their era of chassis. If your a bigger guy (170 and up) I would recommend the EDGE because you get stability from the wider stance when climbing yet the rider has enough weight to control the sled when things get twisty and there is way more aftermarket support for the EDGE than the ZX. I have a GEN2 also and it compares very heavily to a ZX as far as rider input reaction and the way the weight of the sled feels and I can jump from the EDGE to the GEN2 and pull the same line, if your on a tight budget get a GEN2. As far as the 1M goes I can only speculate, I think it would be much like the EDGE, I have never ridden one so who knows. Thats my $0.02. PM8.