SkyNet Wins Outright...
Yes the sentinels are fast, more manoeuvrable, are armed with lasers and can barely be penetrated by bullets (as seen in Matrix Revolutions), the Matrix machines also have vast forces and seem to be swarming everywhere with their central city guarded by a daunting hosts of giant machines that seem to launch a unstoppable barrage of bombs... from this analysis it would appear that the Terminators and SkyNet are royally screwed...
However I disagree... many people have posted that terminators won’t stand a chance against the sentinels. That the sentinels have thick armour and cannot easily be defeated by chemically exploding projectiles (i.e. bullets), however you might want to note that SkyNet’s Machines do not use bullets... they use advanced plasma weaponry that is designed to cut through metal like a hot knife through butter. Their weapons are also long ranged, and the sentinel’s primary form of combat is to physically get close to their targets so effectively a terminator would easily shoot one out of the sky before it could reach the terminator.
It was also argued that sentinels have laser weaponry too, however they can only fire it in a sweeping motion before having to make a loop again to fire at the same target, and the terminators have the advantage of firing in any direction. Not to mention SkyNet has some near indestructible units such as the T1000, T1000000 and the TX (designed to also control other machines) and has advanced knowledge of infiltration and viruses (viruses are a key weakness in the Matrix system which is the source of the Matrix machines power).
SkyNet is also is a learning computer, with advanced knowledge in tactical warfare. It strategizes its victories, rather unlike the machines in the Matrix movie that would throw about 100,000 bombs at one measly resistance ship (what a waste of resources from a military perspective).
Plus the machine city may appear impenetrable, but SkyNet would easily become aware that there is no need to launch a pointless attack on the city when its energy and harvesting fields are OUTSIDE the city, which is the source of all the power for the Matrix Machines. Those facilities are relatively under defended; if humans can escape safely then I am pretty sure a full strike on the facility would be easily accomplished. Not to mention that a few well placed EMPs would drastically reduce the Matrix Machines Army, while terminators such as the t-1000 would not be effected (because there is not core centralised power distribution system within the t-1000, but relies on is non-metallic technology this means a EMP could possibly not affect them, because of they do not need to recharge fuel cells or source their energy from external factors) which means SkyNet can send waves of t-1000’s holding EMPs and the job is done.
And finally, even if the Matrix Machines won, SkyNet is indestructible... why? Easy, it has its time displacement field, if things go bad, it can always start over and using the knowledge of the previous war... win the next war leaving the Matrix Machines dumbstruck. I can go on talk and talking, but I can’t be stuffed anymore... but bottom line is... SkyNet would whoop the Matrix Machines asses... hands down.