The best one is the one that meets your requirments at the lowest cost. The answer depends on what your requirements are.
Everyone will give you different answers according to their own tastes and experience. My preference would be one from www.saleae.com I have used one of their 8-bit analyzers for a couple of years and it works better than some costing many times more.
Bit more expensive, but I have had it over 300MHZ to develop an FPGA design and yes it is 34 channels, bit of a limited memory but it gets the job done , most of the other kit can barely even make the CLK rate of a low end CPU.
I'm 95% happy with it, the only issue is the software could be updated or made cross platform.