are they members of wj?check them all , which will be best because its also depends .ur country ,site etc.
- Straight North.
- Ignite Visibility.
- WebFX.
- SocialSEO.
- Boostability.
- Big Leap.
- Titan Growth.
- Victorious.
a bit dyslexic today?my advice is to go with Black Hat SEO. White hat won't last.
I also vote for Upwork. Have a voice call with 4-5 guys, ask for their best projects and you'll see. The catch with SEO is that someone unskilled can do more harm than good.You can find lots of reliable SEO professionals at upwork. You may also find good SEO experts on social networks like linked and facebook.