Shield/Elec Scrapper or Tank???

I have been trying to decide on my next build, and have narrowed it down to the powersets but can't decide on which AT to play. What are the differences between the two? Can you make any recommendations? Thanks!

Do you want to be tougher or hit harder?

Do you want people to rely on you to hold aggro or do you want to be able to run off and do your own thing?

Do you want to get shield charge before lightning rod or the other way around?

I am looking for something that doesn't need a lot of investment, and I am thinking the damage difference will be partly made up for considering the damage boost with shield and the Aoe help given by Elec. I have played several scrappers lately and I think I would enjoy being "the tank" again. I just wanted to make sure that shield/elec is strong enough to be a reliable tank, that can handle pretty much anything thrown at it, if need be.

I think your best bet would be a scrapper then. In my experience with SD/Elec, everything's usually dead due to your Alpha strike (BU+SD/LR+SD/LR). With this in mind, what's there left to tank when your done?
Sure tanks can handle AV fights and longer battles more easily, but with enough IO investment, you'll hardly notice the difference imo.

Well, I have a BS/Shield scrapper at 50 who's tough enough to main tank the ITF so an Elec/Shield can fit in there... it will take more IO bonuses to get there than a tanker but it'll hit considerably harder.

I also have a Shield/Fire tanker I'm leveling, currently 43. Once my defenses climbed above 30% it was a competent tanker and deals a surprising amount of damage, easily the highest damage tanker I've yet played. When I hit 41 I reached the soft cap with pretty minor IO bonuses so it's much cheaper.

Basically your answer depends on what your priority is. Kill speed with great survivability? Scrapper hands down, they put out considerably higher damage than even the best tanker. Raw durability with decent kill speed? Tanker; you'll have higher base hit points, better resistance and defense numbers and your damage will be respectable, just not on the same level as a Scrapper.

My BS/Shield scrapper's soft cap build probably cost roughly 300 million, my Shield/Fire tank on the other hand was closer to 75 million. Both of these figures do include IO sets that don't necessarily contribute towards survivability; for example I'm a fan of the Gift of the Ancients set for recovery and bonus endurance but it doesn't contribute defense bonuses.

To sum it up, the Scrapper will certainly kill things much faster; it'll need a larger bankroll to reach peak durability. The Tanker will kill slower (but still decently) and will be cheaper to reach the soft cap. Which you go with will depend on what your priority is, both should be competent characters.

My experience is somewhat similar to Awesome's.
In my case I ran a fire/shield scrapper up to 50 with a focus on softcap, +dmg and a little recharge. He cost a fortune and had the performance to prove it.
I then leveled a shield/elec tank to 50, also heavily IOed. It took almost nothing to softcap so I got the recharge high enough to get the nukes down to about 30 second recharge and built up the damage bonus until my Gaussians proc put me over the AT cap.
For fighting big foes I liked the scrapper better but that has more to do with fire's ST dmg than the difference between the ATs.
For clearing missions full of minions, lts, and the like I solidly prefer the tank.
I would strongly recommend a tank but as you can see from my sig I'm a little biased.