Well, I'm partially for Glade, but as a Grass Pokémon addict (What...?) I'm instantly with going for Glade anyway ^^;
But if Reborn is your favourite, flask away!
I'd say go for the reborn if you really like them. Let the look of the pet inspire you,and you might soon have an character idea. To be honest, I like the glade one better. But that's because I'm not a fan of celinox, and the glade one doesn't look like celinox anymore. xD So you being a fan of celinox, reborn is probably a better choice. :)

Go for the Reborn Celinox. ^^ And if you like the Reborn much more, go for it. In my opinion the Reborn is better that the Glade. Glade pets are too cute to give them a character. >_< (Well thats my problem) But i prefer the Reborn one.

...It's biased, but I really love the reborn celinox. pokes her Andre
[IMG]http://i388.photobucket.com/albums/oo327/AkiLovette/celinox_reborn.gif[/IMG] Since you want a pet thats green for Flask, I say reborn, Reborn Celinox are totally green!
You should really do what you feel like doing. You can always get an overlay for it or something.
REBORN. I love the reborn. Much more variety for a character. And the overlays could be easier to make and, in my opinion, cooler.