Giselle looks more complete to me. Beautiful name though!
I like [name_f]Gisele[/name_f] because I have a weird (flexible) thing about double letters when it comes to personal preference. I still like [name_f]Giselle[/name_f] though!
[name_f]Giselle[/name_f] is every so lovely.
I prefer [name_f]Gisele[/name_f]. I also have a bit of a thing about double letters (for example I much prefer [name_f]Isabel[/name_f] to [name_f]Isabelle[/name_f]) but [name_f]Giselle[/name_f] is also beautiful.