ccTLDs are perhaps marginally less reliable given who has overriding control over them (.ly is Libya, for example), but beyond that it's probably pretty low on your list of things to care about.
This is not true if you want email to come from you main domain and you choose a remotely exotic TLD. I learned this the hard way. Don't be like me, choose a boring TLD, worry about less stupid things - there are so so many already.