Are u referring to China Eastern Airline? May I know why know the transit is a trouble? And also how is the overall long hual flight on China Eastern?
There is an expression on FlyerTalk forums - 'Friend won't let friend transiting thru China'. Enough said.
You don't have many options in your situation. There are two non-stop flights - SQ and UA. UA is slightly cheaper. PE will cost you $500-$1000 more compared to standard Economy. With UA you have an option of buying Economy+ (not PE) seat which will be about USD $190 more per direction. It is standard E seat, just a little bit more legroom.
Any other options would be worse compared to non-stop because it will be with stops and/or with stops at locations and carriers which are not greatest to be politely speaking - above mentioned China flagged carriers or Philippines Airlines, for example. The best alternative is to have SIN-TYO-SFO with ANA/JAL but it will be more expensive even with standard Economy, compared to non-stop with UA/SQ.