Both the i4 and v6 for those years have timing chains, you don't need to worry about it breaking.

 

They all have chains. While chains can still break (very rare) or stretch, that would be probably the last thing that fails on the i4 and V6. I'd be more worried about other stuff.

 

Fairly certain the older 2.4L I4 engines have issues with head bolt threads - which typically requires extensive and costly repair. Make sure you're getting the 2AR-FE 2.5L engine, which I believe became standard in 2009 and up. Personally, the V6 is in every way a better engine and will give you a bigger grin every time you hit the throttle at a minimal 3-5MPG decrease. My 07 V6 routinely gets 27.5MPG as calculated at the pump with a 30City/70Fwy average. I don't at all trust the LED info screen's numbers as they are always positive skew by 2-3MPG. I have not driven the 2.5L version, but if you want a reliable family car and power isn't super important, go for the 2.5L I4.

 

Only 02-04's 4cyls have headbolt issues. Supposedly fixed for 05-06 (beginning of the gen 5.5). 07-09 4cyl (07-11 hybrids as well as the 2ar-fe didnt get into the hybrid until the 2012's+) have oil burning problems although at least Toyota has offered a recall on it if you can burn a quart or so in 1200 miles.

OP is asking about 09-10s. 09's have the old 2az-fe, while 10+ have the 2ar-fe. Both have chains.