Arcade is fairly weak with his primary weapon being a plasma defender but his quest is very interesting and
Spoiler you can get the Enclave Remnants to fight alongside you at the final battle at Hoover Dam AND you can get Remnant's power armor: the best in the game if you complete his quest line: For Auld Lang Syne.
His perk is fairly good, giving better healing from everything (food,stimpaks etc.)
Lily is a great melee companion and is also quite funny. She was my first 'human' companion but I haven't used her ever since she lost my Oh Baby! :sadvaultboy: her perk is pretty good: allowing you to use stealth boys for a longer amount of time.
I haven't had much experience with Raul (the ghoul guy) but his perk is very useful: 50% slower weapon degradation and
Spoiler 75% slower after completing his quest.
Also, he is fairly difficult to get :
Spoiler because you have to get to the top of the super mutant infested Black Mountain to get him.
Cass is a good companion. her shotgun is useful at close range but her perk Whiskey Rose isn't brilliant.
Spoiler however if you complete her quest by killing Alice MacLafferty and the Van Graffs, she gets a damage boost making her even more deadly.
Veronica is also a good companion. her power fist is so powerful if she gets close enough. Her perk allows you to craft any workbench item through dialogue which personally I didn't find useful but others might.
Spoiler As she is a member of the Brotherhood, you are granted instant access to the bunker at Hidden Valley, instead of having to "prove your worth." also as she is in the Brotherhood, she has power armour training meaning you can give her any power armour when you get later in the game.
she's also very easy to get.