Hi Nelson.
She was the best women i had encountered.
She is the best women i've encountered.
The point about them is what we describe as perfect tenses. Tenses which describe a completed action. The first sentence exemplifies a past perfect tense; and the second, present perfect. Let’s see.
Let’s start with the second, it means she’s the best woman you “have” encountered from a time in THE PAST until NOW.
Now to the first sentence, she was the best woman you encountered from a time in the PAST until a time in the PAST, and then you speak from NOW. Read the previous paragraph again and this will make more sense. And it would have been more meaningful if you had added something like “until I met Jessica two years ago” or “until she passed away”.
Cheers!