There is no such thing as the "perfect" microphone. As a hardware nerd and after spending +$1,000 on a small collection of half a dozen microphone and having personally tested at least a dozen more I decided to share some of my general recommendations, their price ranges, and some commentary.
Upon request, now updated for 2019. Notable changes include the CAD U37, MXL 008, ATR2500 being removed and the addition of the CAD U1000, Samson C01U Pro, Marantz MPM-1000U, and a bunch of new MXL products as they seem to be discontinuing their old products and introducing new ones. I am keeping both on the list for now, but will remove them as availability drops.
Recommended USB Microphone List
Logitech USB Dynamic Rockband Mic ($10-20)
CAD U1000 USB Condenser Mic ($30-40)
Marantz MPM-1000U USB Condenser Mic ($30-50)
Behringer C-1U USB Condenser Microphone ($50-60)
MXL TempoSK USB Condenser Mic ($50-60)
Samson C01U Pro USB Condenser Mic ($70-90)
Monoprice USB Condenser Micr ($70-90) *note*
MXL 006 USB Condenser Mic ($70-100)
Sure MV5 Digital Condenser Mic ($80-100)
MXL Studio 1 USB Condenser Mic ($80-110)
MXL GXL2600USB Condenser Mic ($80-120)
MXL Studio 24 USB Condenser Mic ($90-130)
Audio-Technica AT2020USB+ Condenser Mic ($130-150)
Rode NT-USB USB Condenser Mic ($160-170)
Shure MV51 USB Condenser Mic ($200)
* - Note: The Monoprice USB Condenser Mic is basically a MXL770 ($85, analog) with a built in audio interface and without the hard case+shockmount.
General USB Microphone AVOID List
Audio-Technica TR2500 - Price inflation, now poor value.
Blue Snowball & Blue Yeti - Poor frequency response.
Samson Go, Meteor, Meteorite - Poor frequency response.
Generic and unknown Chinese brands without a background in music.
USB microphones targeted toward gamers and streamers, untested for music applications.
4 Broad Categories Based on Budget.
Generally I group mics into 4 broad categories based on budget, where you can find similar values among listed products.
$10-50 - Rockband Mic Territory
Below $50 you start entering the Rockband mic range and I recommend against making any significant investments in this price range and instead save your money.
If you have a Rockband mic already feel free to use it. If you can find them for $30-ish the CAD U1000 & MPM-1000U are decent and usable.
$50-90 - Good Mic Territory
Here is the sweet spot where you find the widest selection and a lot of good options. Generally whatever is "best" depends on what's on sale, the things here are very comparable as most are made by MXL.
My favorites are the Monoprice USB Condenser mic (made by MXL) when it is on sale and the MXL Studio 1 if you can find it in the lower end of its price bracket. Otherwise, the MXL Tempo is a good entry-level option in this bracket.
$90-130 - Extra Features Territory
Here is where products start adding additional features like increased bit depth, more accessories, better fit/finish, more bit depth, etc. to differentiate themselves. You are not quite at diminishing returns territory, but we are getting close.
For the purposes of UTAU things here get really blurry. My generic recommendation is the MXL Studio 24 as it is MXL's latest model and its improved DAC (digital audio converter) is its headline feature.
+130 - Diminishing Returns Territory
Above the $130 price range you start seeing significant diminishing returns, the selection of USB mics decreases, and you are better off going with an Analog Mic+Digital Interface route, rather than buying a USB mic.
If you are going to spend in this price bracket wait until that mic is on sale so its at the lower end of its price range or just save until you can afford a Rode NT-USB. Audio-Technical prices are inflated and I don't like the AT2020 at $150.
Why Are There So Many MXL Mics on My List?
Because there is a limited pool of manufacturers that make music recording quality USB microphones. Blue discontinued the Nessie, the only mic of theirs I liked. Sure discontinued their old standby and the replacement MV5 has presents I don't like. I couldn't find musician-centric reviews for the AmazonBasics brand. Other known brands don't make USB products and everything else new is targeted toward "gamers" and "streamers" and is not really intended for music use.
General Microphone Accessories
I highly recommend getting a pop filter and a stand of some sort. If your mic didn't come with a shockmount consider it, though it is not neccisary. I can't recommend any specific shockmount as size and fit vary wildly.
Neewer 6 inch Pop Filter ($6-10)
Pyle Gooseneck Mount Desktop Mic Stand ($8-12)
Neewer Scissor Boom Arm Desk Clamp Stand ($10-15)
AmazonBasics Tirpod Boom Mic Stand ($150-20)
Also Consider: USB Interface + XLR Microphone
At $140 you can get a Behringer UMC22 ($40-60) audio interface and an analog Audio-Technica AT2020 ($75-$100, analog) for the same as its USB counterpart. The advantage of getting USB and microphone elements separately being you can update them separately as needed, can have multiple analog mics, get access to the healthy used analog mic marketplace, and gain access to a wider selection of analog microphones.
Favorite Level Interfaces:
Behringer UM2 ($25-40)
Behringer UMC22 ($40-60)
Steinburg UR12 ($70-100)
Steinberg UR22MKII ($120-150)
Favorite Analog Mics
MXL 990 ($70-80)
Audio-Technica AT-2020 ($75-100)
Behringer B1 ($90-100)
sE Electronics X1 ($90-100)
AKG Perception 220 ($120-150)
Sure PGA27-LC ($180-200)
Rode NT1-A ($200-230)
The UMC22 is a great deal if you can find it on sale. I bought my own on Black Friday for $40 and it is one of the best values on the list. I own it and its UM2 counterpart and honestly feel it is worth it over its brother.
I really really like the UR22MKII, mostly because its extra software features Steinburg collaborated with Yamaha to create. I would buy one if I didn't already have a Yamaha AG03 Miku. I used to recommend, Focusrite but I do not anymore. I sold my Scarlett 2i2 because the mic pre-amps were too noisy. The UR12 doesn't have the fancy software of its brother, but its mic pre-amps are very good.
As for mics you have a wide selection. I listed many of the most popular and some of my personal favorites. Analog gear has quite a healthy used market, I was able to get my Rode NT1-A for $120 off Craigslist.
Don't forget your XLR cables. Make sure you get "balanced/shielded" ones. Here is a listing for 3-foot or 6-foot ones for <$8.
Feel free to reply if you feel I missed something, ask why something is or isn't included, or make your own suggestions.