I haven't played SI or IoH for a long time, but here are my previous preferences:
Lads: Vaughn. Went for him in both games. Failed to marry him in SI because I accidentally proposed to Pierre, and proceeded to subconsciously save, but I can easily label him as my favourite HM bachelor of time, much as I hate having the same tastes as the majority of the fanbase. xD
A close second was Shea, particularly in SI. That guy is seriously amazing. I think the contrast between his cute and simple personality and his obligatory manliness (living in the wild and all) was what did it for me. He was too, too wonderful for his own good. xD
Elliot was sweet, and Denny was great too, but I preferred him in IoH. He seemed more isolated and self-dependant. Vaughn and Shea are definitely my top picks, though.
Lasses: NATALIEEEE!!!! Never actually got far enough in my male file to seriously court her, but boy oh boy was she adorable. A simple design and personality, but so fleshed-out in events and character! I find that this, exactly, is what more recent HMs fail to do with their characters.... (eyes GB)
Ah, and the Witch Princess... Definitely a favourite of mine, particularly
this version of her. It's funny how, as far as favourite girls go, Natalie and Witch Princess are a common combo. xD
I adored Julia, too, but more as a close buddy in my female file. Still, I thought she was great. Which is odd, because I usually dislike the typical blonde, skin-exposing, bubbly types. I dunno. She is the exception.

Lanna was fun to have as a bud, but I'd never think of marrying her.
Damn. That's a lot of useless text. Sorry...