Altera's software is miles ahead of Xilinx's. And their hardware is pretty close, with Xilinx getting the edge.
Can you please expand on that ?
Also what about partial reconfiguration , isn't xilinx the leader ? isn't that important for general compute ?
Place and route in digital circuits is an NP-hard problem. Xilinx solves this problem using analytical place and route (solving a giant system of equations), explained here a bit more: http://www.xilinx.com/products/design-tools/vivado/implement...
Altera's tool uses Simulated Annealing. Historically, Altera's tool has been faster and easier to use, allowing user's to implement larger designs and synthesize them quicker. However, I don't know the state of things RIGHT NOW, but I'm pretty sure this was the case 2 years ago.
Altera's chip design/layout is lacklustre compared to Xilinx's though.
Also, partial reconfig is a very important feature, but it's not used by all customers. Most people just want large FPGAs so they can fit large designs on them, have really fast I/O (Transceivers) and meet timing on their circuits.
[1]http://www.eejournal.com/archives/articles/20120501-bigdeal
Here's a good thought exercise to help visualize the situation: imagine if Intel had insisted on keeping the x86 instruction set closed and undocumented, and, furthermore, that they had succeeded in doing so. For 30 years we've had nothing but proprietary Intel compilers. How much would life suck? How far behind would we be?