I had a magura one, it leaked from the swivel joint unless you did it up tight enough that it didn’t swivel and it blew the head off last time i used it (so I’m shopping for a new one too).
The new fox one looks identical with a different head, ditto marzocchi and manitou, topeak is completely identical IIRC.
I quite liked the old/cheeper Fox ones with all metal parts.
As for losing air when you take it off, are you sure, the hiss you hear is from the air escaping from the pump, the valve in the shock/fork closes before the seal is un-done. When you re-connect the pump it will always read lower as the shock/fork has to re-fill the pump (unlike a presta tyre pump which keeps the valve closed until the pump pressure is higher than the tyre pressure) .