My personnel feeling is that the 356 X is the way to go if you have the budget. Something that hasn't been talked about yet is the numerical IPG tensioning system. This I find interesting since I find it quite useful, more useful in fact than the Gan magnetic system (particularly since everybody just uses the clear magnets) . It's really handy to have the same tensions all round even after taking the puzzle apart and putting it back together. That being said, you can make a very valid case towards the Gan 354 especially if you like smaller cubes. The 356 R is a good cube if you want to take the time to put magnets in. Personally I'd rather not go through the work of putting magnets in when there are so many affordable magnetic cubes these days. However, neither the 354 or the 356 R have the numerical IPG tensioning system, which I personally think is well worth the money. BTW I am slightly biased as I have been using the 356 X since I got it last November.