Sadly this is a choice only you can make and based on personal preference. I would do your own research that might help. If battery life is your main concern I would maybe look at the spec on each watch. Again you have to also base it on usage so how you will use the watch and so on. I can give you my own personal account on the samsung watch 4 I have it on my wrist I don't use it for anything else other then time notifications sleep it gives me over 24 hrs.
Having used the Galaxy watch 4 since launch I can safely say I was sceptical about battery life however now however now 4 months in battery life is very good with Power saving mode and basic essentials on such as notifications I can easily get 2 and a 1/2 days can easily before charging. Also ultra Power saving is there for peace of mind just for that journey home before charging.
You're not alone with your concerns but if you love the ecosystem and play it sensible with a correct watch face you will easily have a lot of enjoyment from this great product I've never looked back.
You will notice a slight improvement in battery life but like most things the more you have on the the more the battery drains, it's a balance Personally speaking I don't have any worries getting through a couple of days the days with moderate use. You can have all the battery life in the world with other brands but does it do thanks but does it do what you want it to and also you have the Samsung ecosystem you mentioned It makes sense to stay connected. I also love the fact that my watch can connect to my phone tablet and phone tablet and earbuds seemlessly.