Ya, Roth for Van Halen 100%. Sammy is the better singer but not the better songwriter for Van Halen style. I see the Van Hagar stuff like that was Sammy's best backing band in terms of talent ("Love Or Money" is one of my favorite Sammy solo songs from before Van Hagar). I wish they'd done more songs like "Get Up" but they leaned into the ballads too much, which was Sammy's fault. Also, it's like Eddie forgot how to play guitar when Sammy showed up. Eddie is Top 3 for riffs with Tony Iommi and Jimmy Page but I don't remember too many great riffs from the Hagar era. Oddly, Alex's playing seemed to improve in those years. Roth, on the other hand, is a nut job, you can see how looney he got with the solo stuff and even with the David Lee Roth Band with Vai, his choices for some cover songs would have driven me up a wall. You're not a comedian, Roth!In Van Halen? Roth. Sammy was a vastly better singer, but Roth’s deeper voice and almost crooner like melodies darkened the tone and gave a lot more room for Eddie to make cool fills, places Sammy or other more rangeful singers would just typically carry a longer note. Plus Sammy’s range brightened up the sound of the whole band, including Eddies guitar, I think all through the Roth era he typically tuned Eb standard or possibly D, Van Hagar era is E standard, and it sounds much more cheery and poppy as a result. In fact that’s what I find so unique to Roth era Van Halen, almost all of their songs have broad commercial and even pop like qualities, yet it has a legitimate heavy metal tone to it. Only other mainstream band that pulled that fusion off so seamlessly was Queen.
As a person, for their individual singing abilities, and their other work however? Hagar hands down.