Definitely [name]Stephen[/name].
[name]How[/name] are you pronouncing the ‘[name]Stephen[/name]’ spelling? Would it be “STEE’ven” or “[name]STEF[/name]'en”?
GOOGLE translate does a nifty thing with this name. The first time you enter it you should spell [name]Stephen[/name] first then click the speaker icon it will pronounce it Steev-en. Delete then spell it [name]Steph[/name]-en, with that spelling with the hyphen in it it will pronounce it ‘[name]Stef[/name]-en’.
Definitely [name]Stephen[/name]. The [name]Steven[/name] spelling screams 1950s to me.
[name]Stephen[/name]! For sure
[name]Stephen[/name]! I am not a big believer in phonetics trumping all. A lot of classic English names aren’t phonetic: I rank [name]Stephen[/name] up there with [name]Thomas[/name], [name]John[/name], [name]Michael[/name], etc.