[name]Harrison[/name] - I like this pretty well. One issue with any surname name is that the kid can kind of sound like they have two last names, and your last name is a familiar enough one that that kind of applies here. Also, looking at your other names, there aren’t other surnames really hanging out there, so is this one a style fluke? Or is it also a family name? It might go well in the middle if so (or just in general). Anyway, this would work with [name]Rhys[/name] or [name]John[/name] in the middle, I like [name]Rhys[/name] better for mixed endings, but maybe wouldn’t go with Hatten all that well.
[name]Owen[/name] - I think this is my favorite for you, I like the feel with your last name. [name]Owen[/name] [name]Rhys[/name] is the best combo - gorgeous - two nicely Welsh names, and no repeated -n ending. Although [name]Owen[/name] [name]John[/name] or [name]Owen[/name] Hatten is perfectly OK.
[name]William[/name] - really pretty tough call between this and [name]Owen[/name] for me! Works with any of the middles, so if Hatten or [name]John[/name] is your true love for a middle name (which I can see being true, since they’re family names), I think this wins points over [name]Owen[/name]. If you want a Celtic name, which [name]Owen[/name] and [name]Rhys[/name] suggest, I think [name]Liam[/name] really sweet as a nickname for [name]William[/name] (I also like it on its own, but greatly prefer the flexibility of a fuller name. My understanding from skimming the internet is that even its Irish use historically really was as a nickname for [name]William[/name] and not as a full name, though I don’t know how true that is). [name]William[/name] Hatten, [name]William[/name] [name]Rhys[/name], and [name]William[/name] [name]John[/name] - it’s a tough call, but [name]William[/name] [name]John[/name] is of course very nicely timeless : D. [name]William[/name] [name]Rhys[/name] is unexpected and has good flow, [name]William[/name] Hatten is unexpected and honorific.