I’ve drank a few Emilia-Romagna producers but have been underwhelmed. I’ve had Drei Dona, Castelluccio, Casali and Tre Monte. Most were under $20 so for that amount I suppose there were OK. I’ve also had the Drei Dona Pruno at $35. Better, but not a great QPR. If I want sangiovese, why would I buy Emilia-Romagna instead of Chianti or Brunello?
In addition to those, Umberto Cesari are very good indeed, however above all others please buy a bottle (or more) of San Patrignano. The backstory is a strong justification to buy (there are many articles but also youtube videos), but the wines are good (and very good value). Consultancy is provided (free IIRC) by Ricardo Cottarella, but IMO the wines aren’t over-made. Avi is the one I’d recommend, though their Montepirolo Cab Sauvignon is also worth trying.
Worth trying the E-R dessert wines as well, if such things appeal, though the top ones aren’t that cheap.
Generally I’d buy E-R Sangiovese for leaner wines closer to Vino Nobile di Montepulciano than Brunello. If seeking something to cempete with the style of Brunello, E-R is not the place to look (IMO).
It’s slightly west of E-R, but Tenuta Mazzolino, in Pavia province, a little west of Piacenza, is making some very serious pinot neros, as well as bonardo and other wines. The sparkling wines are excellent, too.