I have a Skelly Shield, but just got the recipe and made a Defender Shield because I thought it was better, but after looking at the stats it doesn't actually seem any different...
I'm really new and quite broke, so I don't want to equip this new Defender if I should actually sell it...
Quick! What do I do? :)
Defender and Skelly shields are about the same in terms of usefulness, which is to say that neither is very useful. Sell the Defender and make an Owlite Shield.
So much hate for the Aegis ITT. I'll see you fools behind Vanaduke with mine.
I have a Skelly Shield that I only use when entering T3 Fiend strata for its shadow defense. It can take a lot of those projectiles before breaking. I don't bother using it in Undead strata though since I can dodge them easily enough. Otherwise I'm likely carrying Owlite for its Elemental, Fire and Shock resistance. Actually, now that I have a Crest of Almire, I use that instead of skelly shield for fiends... So it is just collecting dust now :/
Aegis is a nice choice too, it has a lot of health. Actually, now that there is a new piercing option, the Barbarous Thorn Shield, I wonder how it compares to the Aegis? Especially given the Sword Damage bonus.
To your question though, given the choice between Dread Skelly and Aegis, then I'd choose Aegis.
The Aegis is stylin', but it has no fire resist or elemental defense. Both of which are huge assets in the final fight with Vanaduke, and most other T3 strata. That said, if you're good enough you could run with a Swiftstike in T3, relying on dodging and shield bumping in lieu of tanking hits with the shield.
The skelly shield is a decent secondary for Fiend levels, but I would get an Owlite series, especially if you plan to use it as you upgrade. Piercing defense on a shield isn't all that useful, as you'll be able to dodge most of the piercing damage attacks. The only possible exception might be if you plan to tackle a lot of giant lichen colonies. Elemental and normal damage is what you need, with fire resist preferably. The reason being that the bullet hell Puppy Turrets will put you through in later levels is best handled by shields with good elemental defense; the fire is for all manners of flamethrowing enemies. You can literally stand in a sea of Gremlin Scorcher fire while hiding behind your Owlite shield.