I like NeedyList, it's annoyingly procedural but the coder does seem to have decent coding habits and I approve. It's like with Gello's ItemRack, I've been poking at it lately and it's not bad. It's annoyingly procedural but at least he's doing his best not to purposefully bloat things out. MCom floored me though, I'm sorry to say that it's exactly the opposite. I say this from a viewpoint of personal taste and I'm entitled to my opinion.
The only reason I object to code like this is because some people wonder why they end up with 5FPS most of the time. :/ I just feel bad for these people. Nobody will ever understand that. Nor will they understand that I also feel bad for PCs running code that makes them go through thousands more cycles than they'd ever need to.
And there's nothing wrong with having an opinion, dammit! People can call me all the elitist arseholes under the sun but it doesn't make my words any less true.
Anyway, yeah, I recommend NeedyList. I'm going to continue to poke at CastOptions though to try and optimize it but ... it's going to take me a while. It's going to take me a long, good while because I have a lot of work to do.
What part of CastOptions are you really after? There's a lot of other addons (aced) that could cover parts of what CO does. If you're after the more complex things, like not breaking cc and things like that I'm not sure, but if it's just self-cast and smart rank casting, then there are alternatives.