I'm really late to this to reply but I chose the regular over the XL having owned both at the same time; atm I own neither.
The XL does have bigger screen, better battery but it feels like a cheap toy compared to the regular 3ds. In the hands it's hollow feeling and has a bit of flex in the casing. It wasn't any more comfortable imo in fact the finish on the XL seemed conducive to generating sweaty palms which I can easily see leading to pre-mature paint wear on the console. The sound quality is noticeably worse on the XL as well.
I really enjoyed owning the DSi XL but the 3ds XL is not for me.
Virtual Hydlide, Bad Dudes