Oktava 012 vs. Rode NT5 for music?
 

Looking to record mostly acoustic strings, piano,
and organ.
Anyone have experience with both these mikes?
Or have any thoughts on which might be a better
way to go?
Anything else in this price range that I should
consider?

That would be hard to say definitively because it would be highly dependent on the instrument and the room, as well as the sound you're hoping for.
I have an Oktava with both hyper and cardioid heads. The cardioid is extremely wide open, almost omni but with a very small null zone directly back. It picks up alot of the room, so if you have a good room it's great but it can pull so much detail out of a bad room that it becomes very noticeable even though it's a great representation of the actual sound in that space.
Of course even with a tested Oktava from the Sound Room like mine, your cardioid head might be totally different.
The hyper head is much more directional and still has very "pleasing" sound. That's the way I'd characterize the Oktava's. They have an open, detailed, pleasing character.
My pair of NT5's are a little more clinical sounding. Fairly flat and low noise, but not as wide open. They are a little light in the bass and a little stronger in the highs.
I would definitely also consider a pair of AT3031's. I think they are more balanced than the NT5's, plus they are a little lower in self-noise and higher in sensitivity. And they have a bass roll-off and a pad built-in. They aren't as detailed as the Oktava, but they can mask a bad room a little better. They are definitely lower noise and hotter than my Oktava, so if you're working with mic preamps that aren't great, the AT's can help a little.
The Oktava's really do require a good shockmount and a minimum windscreen even when used indoors on a stand if there will be any movement around them.

Other options:

Studio Projects C4 and MXL 603S.

The MXL's are $99 each and the C4's are $350 a matched pair with multiple capsules. The Octavas quality has been hit and miss so you end up doing alot of auditioning to find the right one. The C4's were developed with help of Brent Casey who used to work for MXL. Depending on whether you want to swap out capsules or not should be a deciding factor. The MXL603S are supercardioid and work really well, I use them for Drum Overheads, Violin, acoustic guitar and vocals. They replaced my AKG451's as my main go to SDC a few years ago. MXL recently came out with a 604S that has 10db pad and rolloff filter but I haven't tried those.. yet.

Peace,
Dennis

Jay, you mentioned the Oktava cardioids being
almost omni. One thing I didn't mention in my
original post is that I will
be trying to isolate a singer during the recording.
For example, a singer standing 6 feet from a piano,
with each one having their own mic, in an attempt
to get the least amount of bleed. So, given this,
perhaps the cardioid Oktava on the piano
would not be the way to go? For the piano mic,
would I be better to go with a hyper Oktava?
Maybe the NT5? Or how about an NT3?

If you're giving the mic any space back from the piano, then with only 6 feet separation between the singer and piano, I think you're going to get some bleed into both channels no matter what mic you choose. Unless you use a pickup device like a Barcus Berry for the piano, but then you lose the room ambience.
I think this is a case where you want the least off-axis coloration, rather than the most directional mic, because the leakage is going to be there no matter what so it has to sound good in the off channel.
I don't have any experience with the other Chinese SDC mics that were mentioned. A pretested Oktava or a pair from the SoundRoom with both hyper and cardioid heads for both would give you a lot of flexibility.
Not sure if you're really looking for a stereo pair or if you want two different mics on piano and singer. Unless you want a large diaphragm for the singer, or a more specifically vocal mic like an EV ND767 or 367 for the singer, then I think the Oktava, 3031, or NT3 would work for both and be acceptable. I probably wouldn't pick an NT5 for a vocal. Any of these mics mentioned are very useful to have. I don't think you'll be wasting any money, it's just getting to the sound your want with the fewest number of tries. Unless you can rent, borrow, or return, then you'll have to do some guesswork.

For my application of strings and piano mostly,
what would be the opinion of the 012 hypercardioid
vs. the NT3?
The NT3 isn't harsh, is it?
Oh, and what is the pick-up pattern on the 012
hyper capsule? Is it a bit on the wider side
as compared to other hypers, same
as how the 012 cardioid is on the bit wider side
as compared to other cardioids?

The NT3 isn't harsh, it's very smooth and has lower self-noise, but I don't think the frequency response is as wide as the Oktava, especially in the bass.
The Oktava hyper seems to have similar directional characteristics as other hypers that I use.

Do you think the Okatava hyper will sound just as
nice as the Oktava cardioid on a piano?
Like I said, I've got a hyper mic already on the singer
and I'm trying to cut down on bleed

P.S. I'm just miking the piano mono.

Strictly speaking, the hyper would probably not sound quite as good as the cardioid. Practically speaking though it may be more effective for your situation and therefore it will effectively do a better job for your end product.
For a different line of thought, you should also experiment with using a stereo pair placed for a balanced representation of both the singer and piano. That would give you less control in post, but if you hit the sweet spot and you have a good room, it might give the best overall quality.