Just some pricing comments
Sun's 120$ (I guess it is per year) per employee means all company full time staff (academic is different - 1 student = 1/4 full time) and includes some level of support (as far as I recall). It is worth to point out that solaris licenses + virtualisation are free of charge . OS & HW support is covered by same support package (optional but highly recommended)
IBM charges for everything: HW + HW Support + AIX(per CPU or Core) + virtualisation + AIX support (per CPU or Core).
Maybe someone will argue at initial purchase stages, but at the end of the year they realize IBM pricing exactly as I wrote above.
At the price/performance front I would say IBM system price looks higher in
most cases than Sun's comparable performance HW (in my region). Oracle is pricing Power+, UltraSparc VI+, Niagara2 cores with same fractional multipliers and if you put energy costs into equation for the same performance/core, most likely Sun's system will win.
In general, performance tuning depends on apps and admins, but for the time being Solaris tunning tools are more sophisticated, in my opinion.
So, with recent all Oracle SW price increase (~15-17%) I hardly believe in:
"For Oracle products you get about a 6-1 per core advantage vs. SPARCIV+ which is end of life. The Power advantage vs. SPARC64 is 3.7 to 1. The software savings alone makes the hardware purchase free." by Anonymous Coward, that looks like outdated a bit.