Amex Blue Business Plus 50k vs 75k

I read here about applying and not accepting the standard 15k offer for BBP. Within a few days they emailed me an offer for 50k / $6k spend. I know there’s 75k out there, is it difficult to get? Should i just accept the 50k? I’ve been trying to get a better offer on the Amex plat but been stuck at 80-100k for years.