I've had (Amtrak-standard) tasty meals on both. The presentation of Acela First is, in my opinion, nicer. If I was forced to rank meal services I've experienced, I'd say (1) Acela First -- if not for the quality, then for the fact that there's typically something new every season; (2) Auto Train; (3) Traditional; and (4) Flex.Are Acela first meals better than Flexible dining for those who are familiar with both?
I'd say the actual substance and overall quality isn't actually all that different, but alas. The Café Car food does not deserve to be ranked on this list