Skyrim perk tree tiers
SSS Tier (A.K.A. crafting is BROKEN IN HALF)
Enchanting - Can do everything from increasing your damage with weapons to ridiculous heights, to reducing your two favorite magic schools to zero Magicka cost, to making you as resistant to magic as the game will allow. Even lets you make gear that *greatly boosts the effects of the other two crafting skills *(which is where the brokenness of crafting really starts to manifest). But regardless of just how far you want to take the broken aspect of crafting, EVERYONE should boost this to 100 ASAP and take the middle path up to Extra Effect (Insightful, Corpus).
Smithing - Everyone who uses armor and/or weapons should be taking this to 100 ASAP. And this skill is also the reason weapons are MUCH better than Destruction magic as your main offense. Crafting your own stuff is cool enough (and Dragonbone weapons with Dawnguard installed are as good as it gets), but the real power comes from improving your gear. And said improvement is also assisted by Enchanting and Alchemy, which leads to some broken results.
Alchemy - Only reason this is mentioned last in this tier is because it’s, by far, the slowest crafting skill to grind, with the ingredients spawning rather slowly. But make no mistake, it’s as much a piece of the broken crafting puzzle as the other two skills. Even at around 50 skill with the available perks to that point, along with Fortify Alchemy gear (from its buddy Enchanting) you’re looking at making some ridiculously potent Fortify Smithing and Fortify Enchanting potions. Oh, and Alchemy is also a HUGE money-maker if you know the right recipes.
Sneak - A.K.A. why assassins are powerful builds in Skyrim. 15x backstabs with daggers (30x with certain gear) is just too good. The rest of it ain’t bad, either. Silent Roll is a lot of fun and lets you move quickly while still hiding, and Silence is also nice to be able to run at no penalty to hiding. Shadow Warrior, while not necessary, is cheesy bullshit if you do want it.
Block - A.K.A. why one-handed + shield is the best overall fighting style for warrior types. Deflect Arrows, Elemental Protection and especially Block Runner make you a rapidly advancing wall of death against mages and archers with your shield up. Quick Reflexes can also save you quite a bit, and the right side of the tree (bashing) is also really good. Shield bashing in general is pretty close to broken, essentially being a quick free stun any time you do it. Shield Charge is fun, too.
One-handed - Superior to Two-handed overall, since it allows you to use a shield or dual-wield. The former of which lets you shield bash (re: stun) idiot mages and archers before killing them, as mentioned in Block above, and the latter of which is the most purely damaging fighting style. Also, only one-handed weapons benefit from the melee Sneak perks. Just stay away from the weapon-specific perks and the paralyzing capstone (really, who uses backwards power attacks?) and you’ll be fine. All five levels of Armsman, Fighting Stance, Critical Charge and Savage Strike are definitely quality and must-take, as are all the dual-wield perks if that’s the style you chose.
Archery - Very powerful, especially in conjunction with Sneak and the crafting skills. Dedicated archers will want to take every single perk in this skill, pretty much. Unlike its melee counterparts, Bullseye, the paralyzing capstone, is actually worth it since it applies to all arrow attacks.
Light Armor - Better choice than Heavy Armor, overall, since it requires fewer perks to max out, encumbers you less from the start and doesn’t slow you down. Still capable of hitting the damage reduction cap with the crafting skills in play. The extra stamina regeneration from Wind Walker is pretty huge, too.
Speech - Mostly an end-game pursuit, but the left side of this tree (the mercantile perks) is vital toward maxing out your moneymaking potential. The right side isn’t quite as necessary, though Bribery can come in handy.
Alteration - Mostly to get Magic Resistance and, eventually, Atronach. Great to have at high levels, since there magic is generally a bigger threat. With enough passive Magic Resistance from this plus Agent of Mara and/or being a Breton, your Enchanting slots will be free for other things. Also, Atronach perk plus Atronach stone lets you absorb 80% of hostile spells as magicka passively. And, of course, for pure mage builds (if that’s what you want) this is essentially their armor skill.
Illusion - Definitely one of the better schools of magic to spend perks in for pure mages and also for assassins. Assassins definitely want to get Quiet Casting so they can cast Invisibility to their heart’s content without being noticed. And for pure mages Illusion magic does wonders in creating chaos on a battlefield, and the perks that boost the levels of enemies you effect are very valuable. This is one of the best schools to dual-cast, since dual-casting also affects levels of enemies affected.
Two-handed - Not as good as One-handed + shield or dual-wielding on the whole. A sideways power attack with Sweep to hit multiple opponents is nice, though, and probably the thing that it can hang its hat on in the face of otherwise more superior fighting styles. As with One-handed, avoid the weapon-specific perks and the backwards power attack paralyzing capstone.
Heavy Armor - The main reason, in the end, you’d want to go Heavy over Light (besides purely stylistic reasons) is the capstone Reflect Blows, which gives you a 10% chance of passively making an enemy hurt himself. If powergaming’s your only concern I’m not sure that’s worth the extra perks Heavy costs over Light (Conditioning on the other side is kinda important), but if you insist on Heavy, there you go.
Conjuration - A good school of magic to know, but the only perks that should really concern you are the extreme left side, dealing with Atronachs. Atronachs are better than undead for conjured entities, being more powerful plus being available all the time as opposed to just with dead bodies around. Bound spells and the related perks are worthless; actual weapons plus the crafting skills are way the hell stronger.
Restoration - Fairly mixed bag, perk-wise, for a vital magic school. Regeneration is definitely worth it in general for a boost in power of healing spells, and Respite is great for warrior classes. Necromage is great for pure mages since it affects spells from all schools against the undead. Recovery perks for faster Magicka regen might be appealing, as well. On the other hand, Avoid Death is generally not necessary (cool flavor though). Wards and the perk Ward Absorb are kinda tricky: They’re quite useful through a lot of the game, but outlive their usefulness once Alteration, Enchanting and armor skill max out.
Destruction - Generally an inferior mode of offense compared to using weapons (and the crafting exploits associated with weapons), but if you insist on attacking entirely with spells, dual-casting with Impact is pretty much necessary, essentially resulting in a stunlock. You’ll also want the Augmented element perks of your choice element. Shock is the best overall, IMO, since it zaps mages’ magicka and is least commonly resisted, plus its “capstone,” Disintegrate, unlike the other elements’ is actually somewhat worth it. Rune Master is worthless.
Pickpocketing - While the skill itself can be quite useful, the perks are mostly a waste. Only Extra Pockets (more carrying capacity) keeps this skill’s tree out of the very bottom. Poisoned could be fun, I guess, even if it’s better simply to backstab someone.
Lockpicking - A skill that will obviously be used often, but you should never spend a single perk on it. Lockpicks are plentiful enough and cheap enough (and weightless!) for lockpick breaks to not be an issue, ever. You’ll play the mini-game enough times to get the hang of it. That’s not even getting to an item you get through the Thieves Guild questline. And if you don’t want to be detected, just make sure you’re hidden before trying to pick a lock (via stealth), since the mini-game freezes time flow.