What microcontroller to use for a beginner

Hello all! Mechanical engineer trying to be a beginner DIY electronics guy here. I'm thinking of starting up my first, simple little project: A thermistor in your sink that reads the water temp and then dims/brightens a blue LED and a red LED accordingly. I've got an Arduino Uno starter kit and I've gone through a lot of the examples, so I have a pretty good idea of how to write the code and do the wiring.
My question is, for such a little project like this (1 analog input, 2 analog outputs), what microcontroller should I buy? My initial thought was the Arduino Micro. But I really don't have an idea for capacity for projects like these, so I'm wondering if that is overkill. I guess the bare minimum I need is a couple input/output pins, a way to supply power from a battery, and some memory to store and run the code. Is the Micro a good choice? Any advice would be appreciated!

Thanks!

JohannesKepler:
Is the Micro a good choice?

It's a reasonable choice.

...so I'm wondering if that is overkill...

Yes.

These may also be reasonable choices...
https://www.google.com/search?q=attiny85
https://www.google.com/search?q=attiny45
https://www.google.com/search?q=attiny25
https://www.google.com/search?q=attiny13