I think both of the "re-imaginings" are excellent games but I would hardly call them XCOM, they stand on their own just fine.
The problem for me is that so many features that made the original XCOM great are missing in the new ones. A lot of the features are still there but they have been dumped down or simplified to the point where it no longer resembles those features as much anymore.
I am mostly talking about the features in the Geoscape/Management side of things. I really enjoyed having to buy/sell/manufacture and research all the things for my soldiers and base, also being able to allocate scientists and engineers to different projects and not just being limited to one research at a time. There are a lot of other things missing from the new games but I do not wanna list every feature that's missing or that was simplified, it seems a lot like nitpicking to people and I often get the response "you are just seeing the Original with rose tinted nostalgic glasses" a response I absolutely fucking hate.
I get why they did it and I even remember an interview where the game designers stated that they tried out the old method but ultimately went with the "simplified" version because people thought it was too confusing. The original XCOM was really hard to figure out but that was before proper tutorials and introductions, something that is standard in games today.
That being said I enjoy the new games and Firaxes makes amazing games most of the time.
I will be looking forward to Jullian Gollops (original XCOM creator) next game http://www.phoenixpoint.info/