great advice and points above.
any circulator from any serious manufacturer will do the trick.
think about volume and capacity: will you need to circulate A LOT of water, or not?
i probably use my vacuum sealer more than my circulator, but for a lot of different things and purposes. (and no i don't use more plastic these days, on the contrary.)
as noted by
@btbyrd , you don't need to vacuum seal to cook a steak in a water bath. i can regularly bee seen sucking air out of a bag with a metal straw (yes, i have a special drinking straw for this

).
convenience: do you have space, need, or desire to keep a large enough vessel ready to run at all times? my system is ready to go anytime, without bringing out stuff from drawers etc, which makes me use the circulator more often.
and then of course: 'sous vide' means under vacuum, not 'in a water bath' – but the original nomenclature has of course changed. but still:
@btbyrd should name his vacuum sealer Bruno instead of the Joule
you don't need a circulator to cook sous vide … just vacuum and super stable temp. and with a steam oven, the need for bagging is eliminated in many applications.
.