I use servint and like them very much.
I took a look at servint before and I would never go with them as they don't provide true VPS's, at least in my opinion. You only have one choice of OS, as far as I know it's almost completely managed for you, and they use Virtuozzo for virtualization instead of Xen.
Linode is much more open. You can choose whatever OS you want, partition your virtual drives however you want (so you could theoretically have multiple systems installed on different virtual partitions), install whatever you want and basically do whatever you want with your Linode (assuming it is legal). They also use Xen, which does a better job at isolation and makes overselling an impossibility.
Finally, they have an extensive
Linode Library with thorough tutorials on how to do all sorts of stuff with your Linode, and their prices are great.
I also looked at VPS.net but decided on Linode because I had heard many good things through word-of-mouth.
The only problem I have found with them is their storage prices. The amount of storage you get for the price is cost-prohibitive if you need to host lots of data or a collection of larger files. You could use S3 or another provider for storage, but that's a real pain. That's the one thing I really found attractive about VPS.net - you could add "storage nodes" on to your VPS plan for fairly cheap.