You got 2 exhos in there alongside a serious team competition with a 100yr history and a new idea that hasn't seen the light of day.
Tough to compare just yet.
I think the exhos survive just because they have the luxury of catering to changing market needs and fit busy player schedules better. Laver cup for example can go to under-served yet wealthy potential markets like Chicago and feature the best players whom crowds want to see, in a friendly-while-still-competitive format that can't be replicated by Davis cup.
Problem is that they all take time and energy for players to participate in, regardless of whether they are exhibitions or not.
If, for instance the ATP gets its way and there is an International Nations tournament in Australia before the Australian Open - how many players are also going to want to play the Hopman cup at the exact same time?
I don't think players spend even 40% of their energies on Hopman Cup.
There's no need for an anual Laver Cup, but they're trying to milk every drop from Fed as they can.
And I'm not sure if this "new Davis cup" will survive for long.