Very hard to pick a favourite.
I am newish to the world of plecs, used to think they looked really ugly when I saw pictures in books but they have grown on me more and more and loricarids are probably about my favourite fish now.
Of the ones I own, I would have to say I like my Chocolate Zebra Plec (L270) best when I can see him/her - so small and cute, photo in avatar. I also really like my Rusty (L310), he/she is always out and about.
I am getting hold of an Imperial Ranger Plec from Russell later this month and the photos look stunning.
Of the others, where do you start? I probably have a wishlist of plecs longer than my son's Christmas list.
I do like the look of LDA33s and Golden Nuggets. I think I am probably about fully stocked on plecs for now.
Can't really go for anything much bigger as I prefer planted set-ups and bigger plecs tend to uproot. I saw a L25 in my LFS recently. Looked like a giant and cost 100, not bad for a L25 from what I hear.