Need help for 15300 and 15450

[sagla]

Hi guys. Your help is much appreciated. I am in between 15300 pre-owned or 15450 new from AD boutique at similar prices. 15300 is 1-2k more expensive than 15450. I am considering white/silver color for both models. I am not an AP guy and I know blue dials are more expensive and more popular but what would be your choice in terms of esthetic, dial color, and etc. in both models? I do not like the blue color much in 15300 but I like blue in 15450. This would be another stupid question but I am kinda between blue and silver for 15450 if I lean toward 15450. If you guys tried both 15450, I would be also happy to hear your opinions about the two colors.
Also, related to the caliber, 15300 and 15450 use same 3120 caliber but is there any difference or update in calibers between these two models?

I hope my questions are clear.

Much appreciated!