The lemon guava is a bit (to me) on the sweet / tart citrus end of the flavor curve, but nowhere as tart as a Lemon drop mangosteen. They thrive with little attention other than water and fertilizer here and in the years I've had them not once have I found scale or white fly on it. I love them but, so do fruit flies :-(
Ruby supreme so far is my fave, the aroma of one fruit will fill a house with the smell of guava, and the flavor is my reference for what much of the guava family should taste like. Unfortunately I cannot keep scale off of mine, and I'll likely pull it this fall after a couple of years struggling with it if I don't get fruit.
The one of the many that I got called "Mexican Cream" is just OK. Not much aroma, weak flavor, but that's on a sample of one or two fruits its first fruiting season. I can keep white fly and scale off it (both love it) with with water jetting it off or using horticultural oil. I'm hoping it, my Barbie pink (so far NO scale found on it in around a year) and some sort of "Asian white" (gets scale really bad too) will give up some more flavor references.
Of all the fruits I have Guava are the most frustrating to grow. Either they languish and die on their own, or just don't thrive and I pull them. Then there's the mislabeling, Arrrggghhhh...