Definitely balance bike.
But if you want to get a pedal bike and take off the pedals (or, realistically, not put on the pedals), that works (almost) as well. Yes, it's a little heavier, but not so much to avoid it.
(I have balance bikes for both of my kids, but I like buying bicycles a little too much.)
The common wisdom now is to avoid training wheels and I agree with it.