Sinema (a) is a 100% reliable vote on any piece of D legislation whenever her vote is actually needed, (b) has proven herself capable of fooling gullible R voters into supporting her in a manner that the Democrat running for an open seat might not be able to replicate, (c) is representing a purple state where persuasion still matters to a greater extent than in a pure base turnout state like GA, (d) is likely to run ahead of Biden/Harris in a state where Republicans still have some down-ballot strength left and the presidential race is likely to be close.
So, yes (R).
She doesn't support nixing the filibuster like nearly all dems do and is unclear on whether or not she supports reforming the filibuster like Manchin.