Tell me about controllers
There are a lot of good Controllers, depending on what playstyle you want. If you are used to Doms, almost any Controller will seem weak as far as damage goes until the 40s, but they can be a lot safer and add more to teams. My personal favorite is Plant/Storm... Seeds of Confusion is one of the best AoE controls, Plant has good damage (for a control set), and Storm is just a lot of fun (and it boosts damage output significantly).
If you want a lot of control, try Earth... but don't expect any damage with no Assault set to go with it. An Earth / Rad would probably be the ultimate team support Controller but you'd solo at a snail's pace... on the other extreme, Fire / Kins solo very well (especially post-32) but don't really help a team as much as other builds (though Speed Boost and Fulcrum Shift are always handy). And Illusion/Rad can pretty much solo anything with an expensive enough build, though it may take an hour or two (or five, in the case of Lusca) to win the fight.
Cascade, level 50 Blaster (NRG/NRG since before it was cool)
Mechmeister, level 50 Bots / Traps MM
FAR too many non-50 alts to name
[u]Arcs[u]
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I think that Plant is a great starter set for the OP to try as the early controls really give a feel for the whole "Controller" idea.
Yes you do rely on Seeds alot, but since it works so well with the exception of the two types of enemy's that you mentioned I would not really consider that a weakness, espically when you pair it with Rad, if they resist your Immob or Seeds you can still debuff and use your 2x damage AoE and Vines and Creepers to do the job, and you still have the sleep if you took it.
The pet is not that weak IMHO, again debuff whatever it's fighting and it will be fine.
PLANT..
Besides, nothing is better then confusing a pile of mobs and then rooting them to death
So much for Castles "Pet AI fix" (aka the Recharge nerf which really sucks for an Emp).
* Plant is awesome though. Creepers is an amazing power and Seeds is so good that people seem to forget they also get a ranged AOE Hold too. I always feel bad if I'm teamed with an Ice or Earth controller though as you're pretty much guarenteed that you'll be messing up their knockdown patches, even if you hold off Roots. Earth at least has other options but I always feel bad for Ice.