Have a look at our caching solution Evolved Caching. Although Lesti_FPC cache is free, due to the way it (and in fact many other paid solutions) serves cached content the performance is - in the developers own words "not that good". Have a look at this page where the developer discusses his efforts to create Lesti_FPC2 - at the moment unsuccessfully.
We believe that Evolved Caching really is a long way ahead of other caching solutions (free or paid, or indeed EE FPC) both in terms of both performance, and the range of caching scenarios and store setups it caters for. In terms of performance, it is comparable to Varnish easily achieving sub 100ms full page HTML generation times (on our very modestly specced store we consistently get 40ms).
Setting up Varnish for a good hit rate on a Magento store is time consuming and difficult but Evolved Caching also integrates directly with Varnish to give a cache hit on every page you visit, regardless of login status or cart contents (unless you have excluded the page from caching in the extension admin settings). Setup is extremely easy, you just need to use our .vcl configuration file on a completely default Varnish install. Worth noting also that all hole punching is all done in admin, you don't need to touch any code.
Basically Evolved Caching was developed to be an extremely high performing, very user friendly caching solution which addresses all of the shortcomings found in competing products. If you want to have a look at the extension guide then you can do here.
We also offer a completely unrestricted, free 30 day trial of the extension, just fill in the form here, and after purchase we offer a no questions asked money back guarantee.