You will see AL spoilers if you stick around. Whether you will regret seeing them is down to personal preference.
AL ends as a very different game than it started. Personally, if I hadn't known some sort of twist was coming I would have been even less happy when I finished the game. I can't really say anything more without getting into details.
Liam is generally a great character, but occasionally he goes too far and he switches from goofy-but-dependable to downright insane. Those insane moments really undercut the rest, though I still like him overall.
Derek, IMHO, strikes a better balance by being younger and having a tighter variance on his zaniness (though possibly a higher median). He's also showing sudden potential for character growth after the last episode, which would be very interesting if it continued.
Liam does a huge nonsense: the tattoo.
but he compensates by really helping Mc in many situations: he pushes him to go out, he assists him during the coma, he helps him with DICK, the owner of the shop, he helps him in the evening with the HOTs (even leaving him way for the threesome), he intervenes when things they start getting bad with Melissa's stepfather, eventually defending Meghan from him, defending MC from Rena or warning him of her behavior....
all with the little excuse of having cancer, believing he is going to die and having no money left.
Derek certainly makes laugh more, but I wouldn't trust him with another's goldfish either