Nah, HM doesn't think UC1 is the best game in the series, as far as I recall.
UC1 and AC1 fall under the same category for me: Good games on their own that are just outclassed by their successors. I'd have a hard time going back to AC1 after AC2. I could probably play UC1 again though, just using cheats like one-hit kills and the like.
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"I couldn't stand a day without a past or future. I need to live each moment to keep fighting here and now."