I haven't had Glofish, but I have a bunch of zebra danios, which are the same species as glo-danios. They're very active, relatively peaceful fish. They do nip fins sometimes. They're fun to watch - they just never stop moving. They can get pretty big, actually. I have two huge, old females who are almost as big as a large male betta.
The only reason I got normal danios instead of glo-danios is the price. $6/fish instead of $1 seemed a bit high for me, considering I was getting eight of them. I hope you're able to get some Glofish. They're pretty fish, even if they are "unnatural."
Current bettas: ♂Opalo, ♂Granite, ♂Alpha-Betta, ♂Eclipse, ♂Lucky, ♂Honor, ♀Virtue, ♀Innocence, ♀Garnet, ♀Chroma, ♀Tethys, ♀Amaryllis, ♀Goldeen
Tanks: 3g betta NPT, 20g NPT community, 10g 3-way divided, 10g NPT sorority, 5g divided betta tank