I know that on a more passive support like Soraka they work because you aren't making too much of a trade off for stats that may help her, however when you're playing more aggressive supports like Leona is it better to have something like armor yellows rather than the gold per 10s?
In most cases, they are not. If you play Leona or Blitzcrank, you basicly WANT to get early kills, cause else the enemy support will outscale you anyways. So if you take gp10 seals, it throws you behind in laning phase, while laning phase is your only strenth and you should try to get an advantage.
On Leona and Blitzcrank, I wouldn't ever take gp10 seals (Armor instead), cause you only win if you are able to play aggressive. On Taric, Alistar and Sona, GP10 seals are okey if you plan on playing deffensive (maxing heals, allowin the AD to farm). If you want to play aggressive on these 3 too (which I, personally, would recommend) you should get Armor seals isntead.
Some "pro" supports even tend to switch their GP10 Quints for Armor/MS/HP quints.
Basicly, not taking gp10 runes is a high risk high reward action on every aggressive support.
Its a guide for supporting from spellsy, a 2k elo guy. It has a own rune seciton.
I run gold per 10 yellows/quints on ranged supports and I know the lane will be a farm lane.
Leona has to be quite beefy for the first minutes of the game so I recommend armor yellow, armor red, magic resist blue and hp quints.
But gold per 10 quints / yellows are definitely worth it if you assume the lane will play out passive.
Runes Against a heavy poke lane or another aggreissive lane, maybe armor better. My hint is armor red and blues and gold seals and quints
Items: Probably are due if you leave them out, you notice at 10 minute or 20minute mark that even you went 0/0/10 in lane, enemy support has still way more money. If you have at tactic that relies on 20minute game with hyper aggression, then i think its different. Mostly everything depends from situation. If you see good stall champions like shaco, singed, anivia etc etc then yes take them.
Generally speaking, I'm going to say it's not worth it. As an aggressive support, you're going to be in your enemy's face a lot more often and putting yourself in a position to be taking more damage - as AD carries do mostly physical damage, I'd recommend running armour over the GP10 because that bit of mitigation might be the difference between getting a kill or getting killed.
On the other hand, if your enemy is running an AD carry that does mostly magic damage early game (Tristana, for example), it might be worth running the GP10 yellows.
Personally, I use both on aggressive supports depending on my laning partner and the lane combination we are against but more often than not, the armour is going to be stronger and more useful.
No For an aggressive support like lulu, leona, alistar, nautilus, etc, etc. You want to run armor yellows, armor reds, gp10 quints and MR per level or flat MR blues. The reason behind this is you are going to be taking a lot of direct fire from the enemy ad carry and their support by being right up in their face.