Let's discuss how useful you find the various Uniques and artifacts. Here's my take:
Top Tier:
Blaster - never need to worry about ammo (go ahead and store another 5 medpacks!), fires frighteningly fast - so good that if you find one, it's worth changing to a pistol build if you aren't doing one already (I'm also rather sentimentally attached to it since it helped me get some of my milestone wins. If I were to be objective, this would probably be 3rd best, and the spear in its current form best.)
Necroarmor - an immense amount of protection which repairs itself twice as quickly as Malek's. Speed boost, rather than penalty like most armors. If you play carefully, you'll never lose this armor. It's also useful no matter what build you do. (Note that higher protection will result in less damage to the armor as well.)
Longinus Spear - +6 armor on top of everything else? You're pretty frick'n invincible (rumor has it this is getting nerfed)
Very Nice:
Phaseshift boots - movement speed is so essential when facing monster hordes. This is top tier if you don't manage to find any boot mobility mods (Actually I'm seeing fewer boot mobility mods nowadays, I must have been lucky in my earlier games)
Missile launcher - having a magazine of 4 is much more useful that it looks to most people. Rather than having to spend precious seconds to reload between every shot, you can fire four in a row (each more quickly than a regular launcher's single shot), then take cover and load everything back up. This makes a huge different in confrontations with crowds or strong enemies. The added accuracy means that using it on individual targets is much more of a sure thing than with other rocket launchers. Also useful for all builds
Trigun - pretty fast firing, and hits HARD - take reloader instead of son of a bitch (on top of son of a gun)
Malek's armor - sort of like Necroarmor, but weaker. And it gets destroyed much more easily, it's possible that you'll lose it in a sticky situation. Works with all builds
Angelic armor - strong, with no drawbacks. Doesn't self-repair, though
Nice and useful:
Beretta - if you have a pistol build, I think tri-shot works the best if you have a decent amount of ammo in your backpack
Pancor Jackhammer - A double shotgun's damage, but with a combat shotgun's characteristics, and can shoot three times before reloading! Be careful not to run out of ammo though! It works as a secondary weapon even for non-shotgun builds. (Triggerhappy does NOT function with it - I found out the hard way.)
Phaseshift Armor - Speed boosts are key. If you're able to keep your armor intact, this is probably "Very Nice" (and with all the AoMs I've been playing, I've gotten a lot better at not taking damage, and thus preserving my armor as well)
Anti-freak Jackal - with both son of a gun/bitch, you can dig really precise holes through walls. No slouch at dealing damage either, it hits rather hard and is great against clumps. But often it'll destroy some of the stuff you wanted to pick up.
Assault shotgun - a more powerful combat shotgun that reloads a lot more quickly
Gothic boots - an excellent substitute for envirosuits, saving all that inventory space, useful for all builds
Nuclear BFG - most of the time when I use the BFG I shoot 3 shots in a row (to clear out vile et al clumps), so this doesn't act as a substitute for those situations. But having a single BFG shot available without cost every so often is still useful
Nuclear plasma - weaker shots, but free. Free means a lot when it comes to power cells
Minigun - unlike others, I think it does do well with a chaingun build - but you can't use it all the time, or you'll run out of ammo (and sooner than you expect)
Baron, Gothic Armor - can be useful in situations, but the speed penalty hinders running away when it matters
Butcher's Cleaver - If you found it with a melee build (pre-spear), more power to you
Meh:
Hell staff - random teleports when playing Nightmare are incredibly dangerous. I don't even bother to pick up vanilla phase devices anymore. On easier difficulties, this is probably "Very Nice"
Railgun - it's not good for dueling monsters in range (its damage per second is subpar), and it's not efficient for hitting things out of range or in crowds (the BFG is far better) - I only pick it up to get it noted in the mortem, and for the cells. Dervis's demo shows that he doesn't take it either, so I'm not alone in this respect.
BFG 10k - The first shot knocks back the target you were aiming at and often the next 4 miss. It's worse than a BFG9000
Revenant's Launcher - I'd rather have a vanilla rocket launcher, usually I can find a reload mod to attach to it. I suppose if your build had zero eagle eye this might come in handy when using the rocket launcher to engage individual targets at range. I suppose you could also use it in rare situations where you're able to aim the rocket to hit what you want while not destroying desired items on certain tiles.
???:
Dragonslayer - (I figure it's excellent, but I've never actually tried it out. Maybe it has hidden effects that make it amazing or totally awful. It doesn't have an armor bonus like the spear, though, so I'd take the +armor spear over it any day if it doesn't have any hidden effects.)
