Best Bases
Good news! All of the belt bases are eligible for use in LLD. Of course, some are more useful than others.

Leather Belt
Chain Belt
Rustic Sash
Heavy Belt
Studded Belt
Cloth Belt
Chances are you want either a Leather Belt or Chain Belt to maximize your defenses. Rustic Sashes can be great DPS belts with added weapon elemental damage. A Heavy Belt is only optimal for an Iron Will build that is trying to max out its strength; if you’re going Iron Grip you are going to want Meginord’s Girdle instead (see below). I have yet to see a build that actively wants to use either a Cloth or Studded Belt, but if you find a perfect one there is no shame in wearing it. Or, just Vaal it.

Notable Uniques

Meginord's Girdle: If you are a physical attack build, you want to wear this. No exceptions. Well actually there is one exception (see “Magnate”)…
Wurm's Molt: Don’t wear this for the leech. You can’t really rely on leech in PvP. The rest of this belt can be surpassed by a good rare leather belt.
The Magnate: Best in Slot for Puncture builds. If you need a corruption on your belt you can also buy multiples of these for a lot cheaper than Meginord’s Girdle, if you are on a budget.
Perandus Blazon: This is a very niche belt, offering a lot of stats, stun recovery and flask duration. Probably not worth it in most cases though.
Belt of the Deceiver: If you don’t need a ton of resists on your belt to stay capped, and you are some sort of 2-handed physical build that doesn’t block, this can be a nice belt to swap to when facing a high-crit build. That’s about the only case where this belt is relevant, though.
Bated Breath: Sweet belt for any high-ES, hit-and-run build like a caster or trapper. You get lots of ES, huge ES recovery, and even some increased damage. If you can manage without any resists on your belt and you want ES, you should definitely be using this. Alternatively you can use this unique chain belt in the spell damage vendor recipe!
Prismweave: It’s pretty obvious what builds this belt is for. If you want to go all-in on elemental DPS then be my guest. However, most copies of these belts are destined to be used in the weapon vendor recipe to roll the Vicious prefix!

Crafting Belts
Since there are so many good unique belt options, there are really only 2 types of belts you would ever need to craft (ignoring corrupt possibilities):

A weapon elemental damage Rustic Sash that provides more defenses than Prismweave;
A super-defensive Leather Belt (or maybe Chain Belt).
So we’ll assume you are only interested in crafting either of these in the advice below.

Make sure you consider the special belt master crafting mods too - there are a few interesting ones. In particular, don’t underestimate the flask-related mods! Master crafting can also be used to add good resistances and ES to belts, but unfortunately the best master crafting life roll is not very good (44 max).
Leo’s “Increased Damage” mod can also appear on belts, but since these are ilvl28 max (GGG PLZ FIX!), you can’t also roll top LLD weapon elemental damage on the same belt (empowering - ilvl30), which is a damn shame.

Super-Budget: For a defensive Leather Belt, it should not be hard to either find a rare belt with top life and a resist, or use Alterations until you have a nice life + resist blue belt. For an offensive belt, you should just settle for Prismweave, Magnate, or find a good deal on a Meginord’s Girdle!
Budget:
For a defensive belt, roll top life + a resist with alterations, regal, then buy a second resist from Tora’s crafting bench. For an offensive belt, get either a good weapon elemental damage or life prefix with alterations, regal, then buy the other prefix from Tora. Tora’s Weapon elemental damage roll can be really bad if you are unlucky (as little as 8%) so you probably want to aim for rolling weapon elemental damage with your alterations, and settle for the mediocre life roll (35-44) from Tora.
Middle-Class: For a defensive belt, Alt-regal until you get top life and 2 other good stats (resistance or possibly armor, strength, stun recovery or a good flask mod), then add a fourth stat with Tora’s crafting bench. You could also Elreon craft if you regal any prefix onto a 1-stat top life belt. For an offensive belt you are going to want to alt-regal until you hit top life and top weapon elemental damage as your 2 prefixes.
Rich: If you REALLY want a tri-res, top-life defensive leather belt, I’m afraid you don’t have much choice but to eternal-exalt or chaos-spam. Neither of these options is really worth it IMO. It is more worthwhile to attempt to craft a top-tier DPS Rustic Sash this way, but your currency is still probably better spent elsewhere. As far as belt corrupts go, one of the more popular options for LLD is “Grants Level 15 Vitality Skill”. This is a WAY higher level than you could otherwise equip for LLD, and on a high-life character can result in a lot of extra life regeneration.





(links to the wiki you used)
http://pathofexile.gamepedia.com/Leather_Belt
http://pathofexile.gamepedia.com/Chain_Belt
http://pathofexile.gamepedia.com/Rustic_Sash
http://pathofexile.gamepedia.com/Heavy_Belt
http://pathofexile.gamepedia.com/Studded_Belt
http://pathofexile.gamepedia.com/Cloth_Belt