Verified answer

The MXL mic is a very good microphone for recording in a studio environment. It's best for recording vocals or acoustic guitar it's not an especially good mic for recording instruments other than acoustic. It's also not a good mic for live sound if you are playing a gig with a band.

http://www.youtube.com/watch?v=A_TltDaM8dI

The same comment applies to the AT2020. They are both good studio mics for vocals.

http://www.youtube.com/watch?v=wx07A2nlvfI - If you are considering the USB version than I would prefer the MXL over any USB mic.

I would not have a preference (except I do not like USB mics) so, the cheaper mic sounds good to me too. But, the best thing to do would be to go the the dealer and actually listen to both mics and then make your decision. I record through an MXL 990 condenser mic and it's quite good.

Firstly DO NO get the Presonus Audiobox. It is riddled with issues. If you want something in the same price range go for the focusrite Scarlette 2i2. If you can spend $25 more go for the Presonus 22 VSL. It is AMAZING! It comes with the VSL software interface which allows you to apply effects while recording. So you can hear reverb, compression eq and delay into your headphones with zero latency. This makes the recording experience SO good. The 22 VSL is basically an improvement of the Audiobox and presonus removed almost every issue that was present with the audiobox. And if you get the 22vsl, install the beta driver. Anyway moving on to your actual question. Firstly you are wrong about the AT2020. I am not sure if you are looking at a specific bundle, but the default mic does NOT come with either a pop filter nor a shock mount. What you get is mic itself and a thread mount to place it on a stand. This sells for about $65. The MXL 990 comes with a shockmount and case but NOT a pop filter, and this sells for $80. But there are 2 sellers on ebay selling for $50 and $70 respectively. Don't know if it is a deal or something. But definitely look into that. Both mics are good starting range condenser mics that will sound good for vocals/some instruments. But where they differ is in their acoustic pickup pattern. MXL 990 is a Large Diaphragm Condenser while the AT2020 is a cardiod condenser microphone. The MXL will give you a brighter and more crisp sound, but it will also be more prone to proximity effect. As in it will be more sensitive to how close/far you are to the mic. The close to the mic you are, the more bass you get, so if you are close enough you get that deeper radio tone. So subtle changes in distance and direction can be more noticeable. The AT2020 is a cardioid condenser, which will give you a more warm sound, it might sound a little dull to some. It will be less susceptible to movement in distance and direction. Due to the Cardioid pattern it does a better job of rejecting off axis sounds and also it will pick up a little less of ambient room noise, which is a good thing. The MXL on the other hand will capture more room noise, and sound of other instruments which might not be directed towards the mic. Both mics are good for their price point. But personally I prefer Large Diaphragm condenser microphones in general. They are more sensitive, give you that professional crisp sound. And they sound good on voice/vocals and string instruments. If you have a wind instrument though or are a loud singer, I would not recommend it. So it would be the MXL 990 for me.

The AT2020 has a slightly better frequency response in the low area (20Hz instead of 30Hz with the MXLV63M.

I'd go for the Audio Technica, but the MXL might be fine for you too.

The MXLV63