Sixteen of the thirty-six tunes here are powerful examples of the greatest party band of the past twenty-five years. From 1978 to 1985, Van Halen were a showcase for impish, groundbreaking guitarist Eddie Van Halen as well as for David Lee Roth, whose gifts included being a frontman nonpareil and driving Eddie bananas. The latter got Roth thrown out of the band, and in came Sammy Hagar, a technically better singer who also brought a boatload of pomposity and sentimentality to the band from 1986 onward. The Best of Both Worlds mixes the two eras indiscriminately — 1979’s effervescent “Beautiful Girls” sits next to 1986’s ponderous “Love Walks In” —and includes three forgettable new Hagar tunes, the band’s first since 1998. “Runaround” and “Why Can’t This Be Love” prove that Hagar isn’t without charm, but one can imagine Eddie including the Roth songs grudgingly; he knows that’s what the fans prefer.