There are a LOT of messenger apps. Just ask for messenger on Play and see what comes up. There are the flagship ones from the individual providers (aol, yahoo, msn) and then there are the all in one solutions that handle multiple messengers at the same time and even multiple names from the same provider.
Some of the all in one solutions do not work 100%. Some might not be able to send pictures on certain protocols (ex: no pictures on msn) some might not work as you'd want it to (no front facing camera). It is a mixed bag and Only You Can Save Mankind... Urm. Sorry. That's a different story. Only you can decide what works best for you.
Personally I loved jive talk/bee jive back in my BlackBerry days. I love Kopete on my laptop (since I'm a KDE man) and when I'm not in a KDE environment I like Pidgin. Right now I'm not into any messenger on my android devices... I have tried Yahoo (proper) and it is a memory hog as you say.
I'd love to try Beejive on my android devices since I had gotten a lifetime license when I was on BB... but the license doesn't transfer from platform to platform... Sucks. Good luck.