PFF Edge is really just for people super into digging around the numbers and learning moreso about good players in real life. Doesn’t necessarily transfer over to fantasy football all the time, although often it does if you know what to look for. It’s also pretty expensive and the data isn’t always that easy to digest. I use it personally but mainly cause I’m a numbers geek.
UDK is cool but honestly, i only rely on it for Matt Harmon’s reception perception analysis. That and Graham barfields yards created article is what I rely on most every year to analyze WR and RB prospects. If you can dish out the $, I think PFF has more value add if you can spend the time. But honestly, as a next step, I would just shell out for NFL sunday ticket so you can watch the all 22 film and learn to evaluate talent that way. Lots of other options available for free you can use. Some I use are Fantasy Insiders (snap counts), NFL Next gen stats (air yards, etc.), Player Profiler for advanced metrics and athletic benchmarking. The one other guy I follow is Nick who hosts Big Dogs Gotta Eat (BDGE) fantasy. He puts in the work and gives in depth / quality analysis. IMO higher quality than what is provided by fantasy footballers or the UDK. So I would pick up his draft guide if you are budgeting just for 1.