As a person who has and plays both, my response to your query:
1. Yes, the low C is quite handy;
2. The Eb is smaller, so I suppose it is somewhat more comfortable (but then again, an alto sax is more comfortable than a tenor but that is only a marginal reason to prefer it).
Your question ignored what I think is the most salient issue- is a low C worth the extra $? (If you have unlimited funds, and money is not a factor, then I apologize in advance).
The quick response is that for the exact same horn, low Eb v low C you will have to spend more money (maybe a lot more) for a new horn. If you get a used horn, there are lots of Eb horns floating around, but low C's are much rarer and, again, more expensive.
That being said, if all you can afford is a low Eb horn, you can probably play are large percentage of music fine with the low Eb horn, and make due when you see the low D-C, just like a bari player has to with a Bb horn. However, if can get the low C, IMHO it sounds better, those lowest notes really resonate, and when you do see charts written for those notes, (jazz band, orch. pit, sound tracks, etc.) you will really hit it. Further, if you are improvising, those notes really add to your palate of choices.
However, if your choice is between one horn that sounds better vs. the other horn that has more notes, my vote is to go for the better sound, and to start saving up for the upgrade in the future.
Either way, enjoy.