I drop 95% of anime but I pick up some anime again later even If I dropped an anime mid series, I have an odd way of watching it. As for favourite anime that's tough I usually just go with what I enjoyed and can remember; Welcome to the NHK, Hyperdimension Neptunia, Black Lagoon, Genshiken stand out as decent to good anime but I wouldn't give a favourite. I read a lot of manga too on top of VNs and videogames, a few light novels to be honest I can't recall something I've watched/read most of the time unless I end up reviewing it on my site or if it was recent.
Right now I could tell you I liked the shorts series I can't understand what my husband is saying and the ongoing short comical psychotherapy. I have about 4 other series I'm trying out to decide wether I will drop or not; Yuki Yuna is a hero, Log Horizon, How to raise a boring girlfriend and I can't even recall the other one.
I'm also trying Desert Punk and Full Metal Panic watched one episode of each since you mentioned and finished the end of Black Lagoon Roberta's Blood Trail did you see that one? Good god was the ending anti-climatic I could rave about it for days.