Played 1,2,4 and 5 .
Mechanics I would say I liked 4 compared to 1,2 while 5 has formula a bit reinvented so it's different at all in good and bad ways.
Story wise 1,2 and 4 are great, 5 story is meh.
So if you want to try after 4 the 5th... Just tune out of the story, it's not even close to others. Personal stories in 5 are kinda good but overall story is trash.
So yeah Valvatorez main plot is great so definitely get that one if you itching for Disgaea.