There couldn't be a more graphic demonstration of the existence of different routes to the top than Hardin and West, two of country music's hottest women singers. Hardin is 40ish, West is 23. Hardin, married seven times, served a long apprenticeship singing in Tulsa clubs and behind such artists as Leon Russell; West, the daughter of Dottie West, was already a hit three years ago as the duet partner of David Frizzell. Most noticeably, Hardin sings with a rough, catch-in-the-throat cynicism, while West's style is full of lilting sweetness and romance. Hardin's album (RCA), her third solo LP, is full of enjoyable regrets, notably on a duet with Earl Thomas Conley on the Bob McDill-Jim Weatherly tune All Tangled Up in Love. Wayland Holyfield's What About When It Rains and the McDill song that Juice Newton also recorded, I'm Dancing as Fast as I Can, make an emotional impact too. West's third solo album (Viva) includes the charming I'll Dance the Two Step (John Greenebaum-Randy Albright-Becky Hobbs) and a clever Troy Seals-Eddie Setser tune, If I Could Sing Something in Spanish. West sounds especially cheery-voiced and full of the delicious optimism of youth on the title track, but she can even bring out the bright side of such a song as How It All Went Wrong. Listen to Hardin when the situation demands a shot of realism; try West when it's time for an emotional pick-me-up.