On Armor...

Although there are lots of variables, I almost always upgrade the Wanderer coat because it has great resistances in all categories.  Then I just find smaller pieces with some poise.  If I need to go with heavier armor, I'll either just tank up with Havel, or put on the Guardian legs and gauntlets, which actually go well with the coat, if fashion is your thing.  Everything else is situational, I find.

Like many of the previous posters, I use a combination of style and stats, although the first order stats that I'm generally concerned with are poise and weight, and specifically the ratio of poise to weight. Defense and resistances are secondary, since a fast roll or escaping stunlock makes up for a lot. What starts popping up for me are items that go well with a lot of sets, and have good poise/wt ratios. For example, I tend to use the knight leggings and gloves frequently, since they are slightly lighter than the elite knight versions but have the same, decent poise. When I have the extra burden, though, I'll use elite leggings because they are so awesome looking. Havel's gauntlets, and the Giant and Black Iron gloves and boots are also high poise/wt, while being generally easy to match. I also like the eastern gloves and leggings for tipping a build over a poise break limit, since you can get a few extra points for little weight. Sure, there are statistically great combos- gargoyle helm and hollow soldier leggings, for example, but you have to ask yourself how much you care about running around in a loin cloth.

Coming back to this, I suddenly found myself in the position of a large amount of Twinkling titanite (which I usually call Twilight Ore, so forgive me if I say that later). So I decided to look for what it's good on. The only time I really used it before was on Astoras Straight Sword, where that at +5 is similar to a +10 Divine Balders Straight Sword, and Velkas Rapier, which again, seems equivalent to similar weapons. It seemed to me that Twilight Ore did in 5 levels what regular ore does in 15, so that fully upgraded gear was equal.

Anyway, looking at my weapons, I find nothing else really worth it. All the good options just don't fit. But what about armor? Looking through, I find out just how pimpin' the Velkas armor set looks. However, upon upgrading the waistcoat to +5, I find that it is significantly worse than my +8 Sorcerers Coat. Not only does it weigh 50% more (due to all the style, no doubt ) it had lower defenses than a non-fully upgraded Sorcerers Coat in all but lightning resistance, which was only slightly lower.

Is this the case with Twinkling Armor in general? Is it all crap?

And if I got you here, on the subject of weapons, whats the difference between Magic and Enchanted? Seems Magic is preferable if you have balanced Int vs. Str/Dex, and Enchanted is better for pure Int?

Is this the case with Twinkling Armor in general? Is it all crap?

wtf lol I gave you a breakdown of twinkling titanite armor upgrades above, but you can see all of them on the wiki.  If you don't care about looks you have the strongest armor in the game available as twinkling armor (Giant's set, bought from giant blacksmith in Anor Londo).  Here are the twinkling weapons one might care about:

[*]- Astora's (awful unless you just want a divine weapon early and are getting the faith anyway)
[*]- All Black and Silver Knight weapons
[*]- Crescent Axe (Faith)
[*]- Both tracers (Dex)
[*]- Giant's Halberd (speeding through the game only really)
[*]- Velka's (INT)
[*]- Quite a few good shields (stone, silver knight, crest, dragon crest)
[*]- Both greatbows
[*]- Blacksmith giant hammer


Most of these are so-so, but there are some legit strong options in there.  Dex has the great silver knight spear and tracers.  STR gets black knight great axe and giant smith hammer.  Velka's is actually excellent, though most INT builds do want something that isn't magic just in case and they have good options using demon titanite too.  Greatbows depend on your preference, but can be pretty strong.

The Giant's Halberd gets special mention for being junky in PvP but great for running the game.  You need 24 strength to 2hand it, but only need to use a few spare souls + couple crystal lizard kills to insta-max it after fighting O&S.  At +5 with minimum stats to use it the weapon still tears the rest of the game apart easily.  Why is it junky in PvP?  It's very heavy and offers very little you don't get out of other halberds when maxed, and has split damage.

Most people bit the bullet and just farm some chunks, using their few slabs per playthrough.  Chunk farming in new londo works, but often you want a chaos weapon as a backup and in that case it might be more efficient to farm in the kiln via killing the first two black knights (chunk and red chunk).  Of course, you have to actually get to the kiln first .

Twinkling titanite upgraded armor is not all crap, and some of it is quite spectacular. Whether or not an armor is upgraded with Twinkling titanite is not highly correlated with its quality. That said, normal titanite really is used mostly to upgrade the more mundane sets, which in turn tend to be pretty balanced from a defense, weight, poise etc. perspective. For you, that may be all you care about. Twinkling works on the specialty armors, the unique sets, and the sets which specialize in one stat at the cost of the others. Also, worth noting is that Twinkling titanite is purchasable, while titanite Chunks are not.

Most armor pieces and weapons are optimized for a certain situation or a certain playstyle, but you'll find certain pieces that really resonate with your particular stats and goals. The black cleric set, as you mentioned, has less defense than the sorcerer's set, but it has much higher resistance to bleed, poison, and curse, making it possibly "better" in certain scenarios, such as the Depths. There are only a very small number of cases in the game where one item specifically supersedes another in every way, for every situation and build, and I'm sure if I named one, someone would come running its defense and correct me, pointing out that it has a slightly different moveset, slightly better reach, or some other balancing factor.

Yah, I took some time to look later, and I did start seeing some differences. For example, Twilight Ore is used to upgrade the vast majority of non-light armor, with Elite Knight being one of the heaviest non-twillight armor sets. Needless to say that, even if regular titanite produces better 'efficiency' (hypothetically) when you don't have some regular titanite armor doing the same thing, it doesn't matter. There is no regular titanite equivalent to Havels.

Sadly, that doesn't change the Velkas set. High stat defense is nice but I find it rarely comes up for me. Ah well.

Currently, I'm trying out heavier gear on that character. I've strapped on most of the elite knight set (not the hat, not enough Endurance yet) to see how I like heavier armor. I may later choose to slap on Havels Armor and see what it's like to have super-poise. This character is not meant for PvP, but for trying everything. I'll keep in mind some suggestions when trying out new armor, especially for heavier sets.