I think now we left the original topic of Gandalf and Glorfindel for seeking more similarities between different characters, I'd like to mention this: of course there are parallels, and many are interesting, but I think we shouldn't get lost in it. You can make parallels of Gandalf the White and Saruman (as Gandalf himself mentions it, he's "a Saruman how he should be"), Sauron and Saruman, Galadriel and Saruman (! think about it. I'll leave it to yourselves
), Isildur and Galadriel (who takes the Ring and who rejects it?), Isildur and Boromir (!!! This just popped out in my head now - I think this one is VERY interesting), and then you can start with all these folks from the First Age, Fëanor and Celebrimbor (grandfather and grandson, both great Noldor smiths of course, both made something that bound the life of Middle-Earth for long time to come), Frodo and Beren (as mentioned by Elrond), Aragorn and Beren (the fate of one being united with elven maiden), Frodo and Maedhros (both have lost a part of their body - arms namely - to be saved from a burden, and both were saved by a friend, both were in the very heart of the enemy's land, then they both came to get their hands on the most valuable treasure in the world, in the end they couldn't resist to take it for themselves, and both were in pain when carrying it, and both ended with it near a pit of fire)... these are just few which came to my mind without more deeper thinking about it. I'm sure we could think of more, I think this might be for a very long time...