Which Comp is better for League of Legends?

For the money you can get a much better gaming PC from Newegg. The ASUS Desktop Computer M51BC-US009O has a vastly superior GPU with the Radeon R9 270 than either model (at least 4 to 6 times faster depending on the metric used). The CPU is also close to 50% faster than either and potentially overclockable if Asus left the motherboard unlocked.

The closest metric I could find for the integrated graphics in the Lenovo is the R7 340.

Of the two you listed I would take the first since the GPU is faster and the CPU is the same but more energy efficient. The one from Newegg I linked to is vastly superior. You can upgrade to Windows 10 when it arrives.

When looking at the GPU benchmarks megahertz are meaningless. It's all about the number of shader/texture/compute units, pixel rate, texture rate, floating point performance and memory bus.