I'm playing the morally gray, self-serving type with a nice streak who doesn't mind helping her fellows around here and there. That said, choices in companions are fairly low.

I killed myself a set of Rangers whole accosted me about getting my Rep up in three days for their signature combat armor (the stuff you see on the cover of the game) because hey, this is the type of character to wear that outfit. It's a shame it's considered an NCR disguise. But I used it to do some NCR quests to get me an acceptable status with them.
That said, I'm still doing Yes-Man's "Wild Card" questline which may end up having NCR attack me on sight.

Now, to date I've been using Boone because, well, he's awesome. So is Cass. And yet they're both NCR supporters to which the wiki said if my rep got too low, they'd abandon me. Or something along that line.
I've also done both of their respective "Loyalty" quests... If I continue down the road I'm going, will I lose access to the two best companions in the game, mechanics-wise?

Because I'm not that fond Lily, I don't like Raul's lips. Ed-E is stuck in Vault 22 and I can't find her ass. Veronica wouldn't be bad alternative except she's melee. I'd rather have a gunner with me.

Ah well.

You can give Veronica an energy/plasma rifle, you know.

As to the rest...if you don't like Raul or the other NCR neutral companions in the game, that's a choice you have to make. Choices & consequences as they say. But yeah, it's tough sometimes. Decisions, decisions.... heh.

And yes, Boone will leave if your NCR rep falls below neutral. I think he'll warn you once, then next offense he'll leave...and once he does that, you can never recruit him again, even if you get your rep back up. Not sure about Cass...I kinda thought if you kept your Karma high, she'd stick around, but have never used her that long so...

It's hard for my karma to NOT be high in this game, it seems. I even played and beat the game as a Legionnaire, with "Good" Karma.

And I'd prefer not to keep having to buy energy ammo for her.
Still, she's pretty powerful with that fist of hers. I simply preferred a ranged companion because my current character is already melee and I'm tired of Lily or Veronica jumping in front of me.

To my knowledge, Raul isn't NCR, and he is as good as Cass or Boone (his perk is the most useful of all companions, IMHO).

Veronica can be told to use energy weapons, and she is fairly good with them, although she will still switch to her power fist on occasion.

Arcade (whom you haven't mentioned) is not NCR, is pretty good with his default Plasma Defender, and can use Gauss rifles.

I haven't found Arcade yet. Might try for him.

It's true Raul's perk is pretty nice. But I've gotten so used to Boone's T_T

Arcade IS anti-Legion however...so he's going to get miffed if you do many Legion quests/gain rep with them.

I already did a Legion playthrough. Not an issue with my future ones.
(Who -isn't- Anti Legion, though? Out of curiosity)

Raul is not anti for sure.
The rest I don't know tbh...
Arcade is, but can be convinced for a while.
Boone is.

Cass I don't know, but she has strong feelings anti wise, and karma is a problem.
Veronica I don't know, but you'll have to destroy the BoS so unless done right she'll leave.
Lily no clue what so ever.

Cass will tell you that she's a citizen of the New California Republic. I've never gone Legion though so I don't know what she'd do if you did.

his default weapon is strong enough for range combat. which means don't have to worry about replacing ammo. giving veronica a ranged weapon meant that i hard to keep track of how much ammo she had. she went through it very quickly. that is why i like arcade better than the other humans.

if you are into guns, have a human that is into energy weapons. if you like energy weapons then go with a human that likes guns. that way you won't be competing for the same ammo types.

Q-35 plasma rifle from Repcon would be good for Veronica, and it's only one MF cell per shot so it doesn't eat through ammo.