To add to my prior reply:
Because your DM is already giving you one of the primary benefits of Warcaster for free - mechanically resilient seems much stronger:
The +1 to con is essentially the same as just taking an ASI (thanks to the 13 con);
The +2 to saves (which goes up as you level) in addition, so your COn save goes from +1 to +4 (thanks again to the Con bump) is basically a deal breaker right there.
BUT - as a personal preference (since you ARE asking for opinions):
Warcaster, to me, is the more active feat and therefore more fun.
With Resilient - you write down the Con bump and the fact that you are now proficient in con - add the relevant bonuses (which are significant) and move on.
With Warcaster - everytime you make an AoO and the enemy suffers from booming blade your character did that, it adds to the story. Everytime you roll 2d20 instead of 1 on a Con save - you see the effects. Seems more character defining.
It's kind of silly (because, again, resilient's effects are tangible, if passive) but it just seems more fun to me.
Just a thought.