Do new versions have everything old versions have?

[Smashbro29]

I'm just confused looking at this page: https://dolphin-emu.org/blog/2014/09/30/dolphin-progress-report-september-2014/

Do I go for the one with the biggest number? Will doing so ever cause me to lose functionality or a fix?

[RachelB]

It's possible. Occasionally new issues are introduced. By and large though the newer the better. If you happen to encounter a problem that didn't exist in an older version, check if anyone has reported it, and if not, do so, then just hop back a few revisions to before it was introduced.