I am not going to even pretend I don’t use Linkvana, and promote it too (linkvana.info be the domain you’re on right now). Linkvana is actually the first successful link building service that I ever used, and over the last 2 1/2 years of being a member, I have found it to be increasingly powerful and effective in gaining SERPS. As with unique article wizard, I consider Linkvana a backbone system for my SEO and link building campaigns.
The main drawback with Linkvana is the effectiveness compared to the price. I agree with others out there who say that it is too expensive for what it is. So why on earth am I recommending it? Well the thing is, I have a systemized strategy, that highly automates the whole post creation and post uploading for Linkvana, which are the 2 biggest drawbacks to the system over something like Linxboss.
Where Linkvana really shines, is with the fact that you can upload as many posts for as many projects (sites) as you want. There is literally no limit. Right now, as I am writing this, I have around 90 projects/sites within the Linkvana dashboard. Some of these projects have up to 950 links sitting there, drip feeding links to my sites on a daily basis, all setup with the intention of having totally hands off link building going on for years to come.
You can find out WAY more information, including some of my results from using it, here.