Behringer makes some decent ones for the budget-conscious. Also, check out the EV RE320. 95% of the sound and a hotter signal for 60% of the price!
If you need a USB interface with one or two pres, look at the Audient ID4/ID14. If you need more, I suggest the larger Focusrite Scarlett interfaces. If you already have an interface you're happy with and need a bit more clean gain, try a Cloudlifter.
No way do Scarlett pres have the amount of clean gain we're talking for SM7B or RE20 territory. Unless you really get an excellent interface/mixer I would go for external pres.
To be clear, this isn't just an opinion thing--the math is in 'eon1's favor. Scarlett's preamps can boost around ~55dB and a SM7B is something like -80dB with a normal speaking voice. Boosting that to -25dB will be audible, but it's not enough for most purposes and maxing out the preamp will generate some hiss.
The larger, non-bus-powered Scarlett interfaces provide perfectly good results with the SM7B.
Even their 8i6 only boosts about 60dB, though. You can work with that, but that's a little low. I shoot for -14dB to -10dB for spoken stuff, and at that point you'd basically be eating the mic.
The article you linked was using a Cloudlifter with the SM7B, which is a preamp on its own.
I'm looking at the scarlet 18i8, I want four mic pres and will try with the 4-channel cloudlifter. 25db from the CL and another 25 from the interface ought to sound alright
Yeah, that should be completely fine. Presonus has a 8-channel preamp that's about the same price as the 4-channel Cloudlifter, too, btw.