It's impossible to say for sure what's a vanity address and what's generated purely at random, but 1CFBdvaiZgZPTZERqnezAtDQJuGHKoHSzg is 34 characters with no digits in it other than the initial '1'. That may well be a vanity address. Then again on average 1 in every 515 34-character addresses you generate won't have any digits in them other than the leading 1, so possibly not.

The address with the longest initial list of lower-case letters is 1yaniraswqyghuJKCRrGwJUA2HakWtRad, and is clearly a vanity address since it appears in the same transaction as many other vanity addresses.

Edit: I just found this one:

1QBDLYTDFHHZAABYSKGKPWKLSXZWCCJQBX

It belongs to etotheipi, author of the Armory Bitcoin Client, and was found using vanitygen, as he said in a bitcointalk forum post:

Yessir! I got a little crazy with vanitygen and succeeded. It should've taken about 70 days of computation time but I got lucky and found it in about a week... (notice no digits either, only uppercase letters).

Unfortunately, it's so cool that people don't even recognize it as a Bitcoin address :)

There's this thread on bitcoin talk:

https://bitcointalk.org/index.php?topic=90982.0

I personally generated this address: 1BoyishnessfwHq3wSkCkJ7iafUdjhghfU which is the longest one I'm aware of that's not mixed case. It was generated by feeding oclvanitygen a large number of potential prefixes from a large wordlist.

GEnesisReVC

1GEnesisReVCQG641yERVQgStUvqH6S9U2

On Mac Pro with GPU it was 9 days to have 50% chance of genesisre (not case sensitive)

Was using https://github.com/exploitagency/vanitygen-plus

What I really like about this address:

• capitalization of GEnesisRe
• VC suffix
• memorable U2 ending
• capitalization right after VC
• capitalization just before U2

OK, so right now time to raise some money and open a VC fund investing in regenerative communities - independent food, energy, water production and focus on education and new post-scarcity paradigm economy.

EDIT / UPDATE: Out of curiosity tried running the command as if I was to bruteforce it with the exact capitalisation:

./oclvanitygen -d 1 1GEnesisReVC Difficulty: 9883693997182075238 [20.44 Mkey/s][total 398458880][Prob 0.0%][50% in 10630.3y]

With -i (case insensitive):

./oclvanitygen -d 1 -i 1GEnesisReVC Difficulty: 18982355007608803 [19.72 Mkey/s][total 230686720][Prob 0.0%][50% in 21.2y]

Bottom line - got lucky, incredibly lucky.