Metronome - Electronic? Wood? Plastic?

I've been buying alot of different kinds of metronome but wooden one seems to be the best.

It just the acoustic warmth that is there seems to be very musical.

Beep that those electric one produce seems too rigid or cold for me. Especially if you are playing classical or any acoustic instrument you would want to invest in plastice one or wooden one. (one with blade that is)

Unless of course you need the resolution of 1 bpm or less but for practice purpose that shouldn't really matter. 2-4 bpm per notch is enough.

Because unless you are playing with a computer there is virtually no way you will be playing at the same tempo throughout the song. Music is much more than that.
Push and pull that drummer creates.. or pianist does feel that too.

Music is not math. It's continuous flow. There should be some degree of order but absolute spacing between notes but you don't play music as written on the sheet music.

each 8th note, quarter note, 16th note, dotted, triplets has their meaning and appropriate timings. (i don't mean you should play 16th notes as dotted 8th notes of course)

Your interpretation or composers intention is much more important that keeping a solid mechanical tempo. Dynamics, expressions they all depend on how they are put together.

People who can purposefully decide which speed they should go or they want to make it go and put them all together are the one who play amazing music.

Try to keep those two different things in mind.
When you practice you can aim for rhythmical accuracy so you will be executing all action you need to do when you play. It's very hard to be able to do what you really want to do. Solid technique will give that freedom everyone wants.