https://www.techspot.com/review/1386-amd-ryzen-5-1400/
They test it against the i3-7350K, which is faster than the i3-7100 you're considering.
Short answer: it blows the i3 away in application benchmarks, & in games it was competing more with the i5-7400/7500 (they listed the i5-7500 as their testing machine, but every benchmark graph lists the i5-7400). Basically, it's a much better all-around performer than the i3-7100 could ever be.
The only possible area where the i3-7100 can compete is in price...& even then, at best you're maybe only shaving $50 USD off of the total system cost (since they both use DDR4 RAM), which isn't enough to make a significant difference in choices elsewhere in the system (maybe letting you add another 1TB HDD, at best). I'd still go for the Ryzen 5 1400.