That's not my call but JuicedLink and Beachtek both originated in the consumer marketplace for casual users who wanted to use XLR microphones. Field mixers (which are much older and more mature in the marketplace) are targeted at professionals.
Both do the exact same thing to the extent of...
Personally I'd avoid both JuicedLink and Beachtek in favor of a one or two channel field mixer. Compare the functionality of an Azden FMX-22 ($294 after rebate) with what JuicedLink and Beachtek are offering.
If you're totly nuts (like me) you can get one of these!
IMO 'sound production' is best learned by doing, at a community college, or both. In a structured environment (as I'm sure you know) they're going to trot out material you may already know better then the instructor.
I really don't have a good answer but to start I'd look at Tweakheadz · Guide...
What is the rest of your chain/gear? Do you have a vocal booth? If you're going directly into the PC via USB then I'd personally pop for the Yeti. Don't skimp on sound treatment!
Discussing 'best' vocal mics is like discussing 'best' chardonnay wines... past a certain point it's more subjective poetry then quantifiable value. For my money once you get past $300 in large condensers you're into diminishing returns.
I've had a Sound Devices USBPre 2 for about two years now. Very robust, and Sound Devices has a great rep for customer service (not that I've ever needed any). The only down-side is that the USBPre 2 was cannibalizing Sound Devices more lucrative field mixers so they've jacked the price up $200...
If your computer speakers are external, powered, and connected to the computer, can you not connect them to the headphone output of the Scarlet? If you're using a laptop with integrated speakers then, yeah, you're screwed.
I paid $10 for a quite decent pair of Logitech speakers off of Amazon.
Personally I use Sony Movie Studio Platinum Suite.
The latest version of the app comes with
Movie Studio Platinum 12
DVD Architect Studio 5
Sound Forge Audio Studio 10
50 Sony Sound Series: Production Music soundtracks
Red Giant Magic Bullet Quick Looks
NewBlueFX 3D Titling and Video Effects...
Three thoughts,
I really like the production values
I'd like to know what camera you're using
And if the guy you're filming is making real money at this.
Actually, forget that last question... if the answer is 'yes' I might shoot myself.
Given the caveat that I don't know what I'm talking about I find that a good large condenser will sooner highlight the inadequacy of one's recording space then will a dynamic mic.
My MK4 is female... it picks up EVERYTHING, whereas my SM7B must be a guy because it ignores a lot.