I'm flying to Israel on El Al the end of December. What should i expect from a 777 and 744 coach class?

If the plane is full "coach is coach".

But I find the 777 generally feels more spacious. But alot has to do with how the seats are configured. Call El Al and find out whether the planes are configured 2-5-2, or 3-4-3, or whatever.

Personally, and I've expressed this before, my only concern is "that the plane takes off, and it lands" - everything else is a bonus!

as a seasoned traveler and aviation expert I personally feel like B777 hardly compares with the Airbus(es)from a (coach) passenger standpoint. This said try to avoid the 2-5-2 config by all means or if you have no choice seek aisle seat on the window side.
Enjoy your flight.

The B777 is just more comfortable, less noisy, more spacious inside and more modern than the 747.

BUT, really, does all that matter? You booked a flight, you'll get on whatever aircraft will be at the end of the tunnel...

So get yourself a good book, ear-plugs (which reduces the engine noise significantly!), watch a movie, drink lots of water, eat just a little, be calm, and make the best out of a long flight.

So how was your flight?