Well, it might be the SM81, but that is not in the same price class as these other mics listed. Of the three you list here, I own a pair of all three, and I believe the Octava is best hands down. I record my acoustic using a stereo pair and it sounds great. Buy the MC-012s, but buy two, not one, you won't be sorry.
the problem with buying any octava's is the huge quality difference from mic to mic...especially from the evil empire(git cent).they do sound good for acoustic guitars though finding a matched pair for stereo will be quite a feat....the 'best all around' is not on your list and i can only gather that price must be a part of this...i will say that i will never let a c-1000 close to my acoustic guitar....the marshalls ive only heard sparingly and they seemed okay....if you dont care about budget then buy neumann k-184 or shure sm-81 or audio technica 4051 or akg 451'sthese are really good mics and will last you a lifetime of recording...
According to Harvey Gerst, the MXL 603s sound "almost identical to the Oktavas." So at $80 each I would buy one or two of 603s until I could afford to take a considerable step up.
BTW, there was a thread recently where some retailer is selling a matched pair of 603s with case and shockmounts for $176, I think. Do a search, because that IS a sweet deal.
The 603s do sound good on acoustic guitar IMO. The C1000 doesn't.
I have both the Marshall & Oktava mics. There are subtle differences but you can basically flip a coin. They're both fine mics.
The Marshall IS $30 cheaper.
I hear a more noticeable difference than Harvey does. The 603 sounds "boxier" to me in a way . . . which is actually a good thing, to me, on accoustic guitar and mandolin -- it really highlights the sound of the wood, and it's modest high end boost makes it sound slightly fuller, IMHO.
I definitely like the 603 better on mandolin, but I also give the oktavas a slight nod over the 603s on drum overheads.
If you can spring a little more cash, go for the Neumann KM184s. Possibly the last SDC you'll have to buy (except for another KM184 if you only purchased one, like me!)
I have 2 adk sc-1's they are fine sounding mics...they are at least a small step up from the octava's and the marshall but like any inexpensive condenser they vary a lot from mic to mic...some of the adk's can be noisy and some have a big bump @500hz and another at around 2k..try em till you find one or two you like..the audix scx-one is another reasonably priced condenser that might be considered
I own both the SM81 and the 603s. I honestly like the sound of the 603s for accoustic tracks better. In fact, the only thing I'm using the SM81 on at the moment is high hat.
... here is a link to a review of the 603. MXL Reviews
I have the Oktava's, but mostly use them for overheads. They're OK for acoustic, but have no bass cuts and are very subject to boom. Mostly I'm doing it all with AKG C414B-ULS and Shure SM82, a weird obsolete mic.-Richie
I've only used the Oktava mc 012 and like it a lot. The acoustic guitars were recorded on "I Love You" with the mc 012 run through a Joemeek VC6Q. I was very pleased with the sound. You can hear it on my ampcast page.
I just got a pair of the Oktava's and I think they're pretty darn good. They made my acoustic sound better than the overpriced LD condenser they used at a pro studio a couple years ago.