I really enjoy romantic subplots that are done well, but I'm not as fond of romance arcs.
I'm... not actually sure I'm aware of anything like that! Oh dear.
Samurai Champloo (and to a lesser/more backstory-oriented extent, Bebop) does have a fair number of romance-centered or involved episodes, but I'm not sure if they'd qualify as full subplots. I'm also probably not a good judge of "well done," unfortunately.
While I do enjoy comedy, I like Log Horizon because it takes itself a little more seriously than, say, SAO. To be fair, though, The Devil is a Part-Timer is hilarious, and I like that one mostly because of comedy.
Magi's a bit on the silly side, but it definitely gyrates between that and deathly serious. Bebop/Champloo tend to go for darker humor, ie the world is serious but still ridiculous at times. Kill La Kill and Gurren Lagann tend to be similarly serious-yet-silly, just not as dark. Kill La Kill definitely goes further with this, and runs largely off of "the world is ridiculous because and/or and so everyone living in it is ridiculous."
Afro Samurai has a handful of quips, but doesn't usually go for humor, as such. Little Witch Academia, as might be expected from cute girls doing cute things, has a lot of humor or at least things intended to make you squee. I find it hard to comment coherently on humor in JoJo's, partially because of the varies-by-season thing and partially because a lot of the situations are ridiculous enough to be funny even if they aren't explicitly highlighted as jokes... but of course, what counts is going to vary from person to person.
I don't really care about fanservice, so that's not really a redeeming characteristic of an anime.
That was more of an advance warning, so you didn't get halfway through the first episode before suddenly going WAIT WHAT YOU NEVER TOLD ME THIS WAS PORN.
But trust me, it's awesome.
I like having at least one character I can relate to in the anime, so unrelatable characters is a big minus.
Mmhmm, common issue. Lessee...
To be honest, I wonder if this might be one reason Magi has kind of a "generic enjoyable anime" feel to me. None of the characters I'm familiar with so far are particularly inspiring or anything, though most of them aren't dislikeable either.
Bebop tends to have at least one character everybody likes, though "relatable" might be a bit trickier. Still, they've got a decent range and most of them are reasonable on some axis or another.
Champloo, much as I hate to admit it, is a bit trickier. It's only got three main characters, two of which are murderous swordsmen and one of which is a scheming waitress. Still, a chess player, loose cannon, and goofball give you some variety.
Afro suffers from the above issue even more. It's not really a "watch this because this guy acts exactly like you would" kind of thing, or at least I hope it isn't.
Hellsing has a few more characters but similar issues to the above.
Gurren Lagann has a pretty big cast, though obviously some get more spotlight than others. You'll
probably like at least one person out of the main duo/trio, though.
Kill La Kill and Jojo's Bizarre Adventure are probably the big winners here. They both have decently large casts, especially Kill La Kill, and everyone is so ridiculous and awesome it's hard not to find
something you like. Standard eternal warning about different JoJo seasons varying from each other, though.
IO mentions Afro Samurai and doesn't mention that delicious Samuel L. Jackson voice acting. Shame, Ferrousbird. Shame.
I... yeah.
Really you could recommend absolutely anything whatsoever that was made by Hayao Miyazaki and/or Studio Ghibli, as there is not a single bad pick in their repertoire. It just feels lazy to do that though, as it seems like such an obvious answer.
I'm not that fond of them. They're alright, but kind of pointless, preachy children's adventure things that don't tend to really interest me much.