They're both bottom of the range, but don't let that worry you. Xenon isn't made any more, but there'll be no problem getting hold of Campag 10 speed stuff for quite some time.
As for which is better - that's down to personal prejudice preference. TBH they'll both work fine.
I have the xenon via nirone. Shifts beatifully. Far better than Sora, absolutely no contest!! No problem with the hoods, perfectly comfy for me. As they said, it's a case of suiting yourself really.
Bike shop said the xenon is as good as shimano tiagra and I can't argue with them having put a 1000 miles in on it.
BUT it's an Italian bike, has to be campag...
Anyway, here it is..I'll be riding it home before long
I've never had Xenon but I've Sora on one bike I find it uncomfortable between the thumb and fore finger. Shifting is also a pain with sora, I can only shift the thumb trigger when I'm on the hoods (ie not on the drops), with my campy (Veloce) levers I can do it on either. I would like to do a quick feel of the bars first and if Xenon was similar to veloce I'd go with it.