300m
I have a 99 300m and i love it. It's got plenty of power, it's extremely comfortable, Interior is great. Lots of room in the front and back seats. Power everything, Exterior is great.
Though a Sebring Convertible would be nice too ...
I don't like Camry really ... It is a very solid and reliable car ... but I don't like the puny I4 .. and its V6 is kinda lacking in power IMO. It does get better milage and you can get a 5 speed ... It doesn't have nearly as many doodads as the 300m ... (i guess these are little things ... ie .. leather steering wheel, infinity sound system, slightly bigger rims, memmory seating, automatic climate control, integrated garage door opener, Standard leather seats in 300m, optional in Camry ... etc etc etc ...) ..
Maxima's are nice, I was considering a used Maxima back before I bought my 300m. It has many of the doodads that the 300m has, and a nice powerplant .. but I like the comfort level in the 300m ... its a wider car .. and there is more space.
Test drive the ones you like a lot, and pick your favorite. the Maxima or 300m would be my top 2 picks.