What is the best NHibernate cache L2 provider?

I've seen there is a plenty of them. NCache, Velocity and so fort开发者_运维百科h but I haven't found a table comparing them.

What's the best considering the following criterias:

1. Easy to understand.
2. Is being maintained lately.
3. Is free or has a good enough free version.
4. Works.

I can't speak for what's best or worst, but I'll throw in my experience with NCache in case it helps.

Disclaimer: NHibernate and I had some disagreements, we have since gone our separate ways :)

The Good

• The performance was great
• The support was great, it's well maintained (I'm speaking to status as of ~6 months ago)
• It has a free version (caveats below)
• It worked as well as possible, but I had issues with the base level 2 cache provider implementation...but this was a problem on the NHibernate side with HQL, not the NCache side.

The Bad (For reference look here)

• The free version had it's limitations, they are strategically put there no doubt, but for our project ultimately we couldn't use the free version because of some key features not available. The below restrictions are on the FREE version.
  • Key Based Dependency is not included
  • None of the database dependencies are included
  • No 64-bit version

Those were the sticking points on 2 different projects for me...however aside from those, no problems and I was happy with the simplicity of install and configuration. If the above aren't sticking points/requirements for you, I do recommend giving it a shot. It took me less than 10 minutes to get a server up and functioning as our L2 cache.