I'd sit out and wait to see what the Watch 5 offers (and what Samsung with throw in as an incentive) if you're in no rush. Be a win win situation - see what it offers and go for it, or pick up the Watch 4 for cheaper as they'll drop the prices soon as 5's on pre-orders.
Personally though I've had the 4 Classic since launch day and happy with it. Battery life for me is around 3 days on a full charge.