We have a SplashAbout float jacket. It is very nice, but the size 1-3 is only just small enough for my 19 month old daughter. Other than that it is brilliant, and she loves zooming between the two parents whilst wearing it.
When she was 1, I was mostly swimming around with her on me, splooshing her around the pool, and letting her jump in off the side. I only really felt I wanted the float suit at about 16 months or so when she started launching herself off me and needing catching.
They also do a float suit which apparently has a smaller range it fits, so might be better for a smaller baby.