Although your Commander may very well be the most important card in your deck, we would suggest that if you are building your very first list (we built our first when the format was still called Elder Dragon Highlander), that you may be well served in deciding on your individual playstyle and choose your colour(s) first
Impact on the format if banned: While I personally always run 1 in my mono-white sideboards, it's use is limited
Notably, there arent any better deals at worse conditions, either
Being aware of your specific style can help
Type Line : Legendary Creature - Elemental Couple Message: When this card enters the battlefield, create two 3/3 red Fire creatures
Spirit of Winter will never reach the heights of the D23 Elsa - and the price may go down if the meta stops favoring the card - but it's worth a decent amount as far as trading cards go