Overall, I think that OPTIMISED should be the word that stands out the most, so see if the designer can modify all of the concepts to reflect this.
#1 - The 'O' is too hidden and the first thing I see is 'ptimised' only. It really doesn't tell a story or reflect a particular style or how you want to brand yourself.
#2 - I agree with Christina. It does look like a coat button, and when scaled down further for stationery pieces, for example, it will get lost and won't be easily recognizable. Be careful with Web 2.0 types of logos. Although, trendy, make sure it can look good, stand-alone, without the 3D effects.
#3 - I'm not really sure about this one - like #2, when scaled down any further, I won't really see what is within the circles. What message is being conveyed there? I'd request to see 'Optimised' stand out and see if there is better use of the spheres.
#4 - This is nice and simple, but are you conveying a feminine touch in your services, using an elegant typeface? Have your designer show you this with a darker hue of gray. It will get lost in grayscale versions.
#5 - This one is too 'techy/software' related and doesn't reflect the work of a VA, unless one of your specialties is in the IT/Tech sector. I like the colors, though. The upside down V has been overdone way too much.
Overall, I'd select 3 or 4 with modifications suggested and also based on how you want to portray your image and services.
Good luck and show us the final result when the project's complete.