My vote would be pineapple gauva....Feijoa sellowiana. We have a problem with fruit flies growing strawberry guavas outside here in South Florida. In any case, the pineapple guava is a smaller tree. I have grown both.....I yanked the strawberry guava and am still growing the pinapple guava although it has yet to fruit. I have bought the fruit in the store, though. I enjoyed eating it.

I second Pineapple Guava...I've had mine for three years, next month...It flowered for the first time 6 months after I bought it. This is the first year I have "one" fruit,LOL... Personally I prefer the taste of PG. PG can also take temps 15° with little or no damage according to my Ortho Citrus book...Luckily I've not had to test that temp. and hope I never have to,lol...We had a very bad "freeze" here this winter that almost killed all my Mango and Lychee trees, yet my PG had NO damage at all. But you live in zone 3...so you will have to bring yours inside for several months...

Oh, I've also read that you need to have two of them to cross pollinate each other. I also have a Bush PG planted about 8-10 Ft away. Unless there is a variety out there that is self pollinating that I'm not aware of? Good luck!
Here's my Pineapple Guava tree...

And the blooms are edible on the pineapple guava! Pretty tasty.

the problem is I don't have room for two trees since I'm getting many more citrus and magos and such so whcih one was self pollinating?

There are apparently self fertile cultivars. Check out the CRFG article on this

Here is a link that might be useful: FEIJOA/PINEAPPLE GUAVA