XCOM is a beautiful game with a high production value that seems to serve as a tribute to its fans 20 years ago. Fully animated cut-scenes and a Hollywood-styled soundtrack gives the game a cinematic quality that would bring tears to hardcore XCOM fans of the early 90's. In terms of the base management, I love the little animated details in the facilities once you've built them and also the strategy elements in optimization of the limited spaces you can use for building.
If you've played the recent Shadowrun Returns, the game uses the same turn-based combat mechanics, but XCOM's combat options, enemy variety and random environment setup makes this play-style truly addictive here. Other than your gear, the hit-or-miss system heavily depends on your positioning within the environment and certain soldier abilities make height and "extra tiles" coverage an advantage you wouldn't want to miss, thus rendering movement strategies engaging every time since the maps are random.
I love how the game fuses the importance of both base management and combat missions that go in hand-in-hand where on one hand, base technologies are needed to produce funds and upgrade your soldiers' gear, and on the other hand, successful combat missions bring back the materials needed for such upgrades to be possible. The learning curve of XCOM is actually quite steep, even for strategy fans, but the time spent on it is worth it, as it is a top-notch game.