Google actually stopped
publicly updating PageRank in December of 2013, although this doesn't mean that PageRank is no longer a factor (just one that is no longer publicly updated). The reasons some people still use it (especially those who sell inbound link packages) are as follows:
- They haven't heard about PR being obsolete (well, publicly obsolete).
- They're in denial about PR being obsolete.
- They understand that PR was a widely known metric, so they know it's easier to sell backlinks as "PR 8" rather than "DA 8, mR 6, PA 62, etcetera".
- They're terrible at their job and do not keep up with updates or news regarding Internet marketing.
As for tools, try using the Moz Toolbar or Majestic. Moz uses the metrics: MozRank, page authority, domain authority, domain mozRank, mozTrust, and domain mozTrust. Majestic uses Trust Flow and Citation Flow. I personally use the Moz Toolbar in conjunction with several other methods to determine the SEO competition for a keyword and it's been working out fine for me.