Notice that Hilton has two hotels in Prague - Hilton Prague and Hilton Old Town.
I like them both, can't decide which I prefer.
Both have good lounges (I think most people prefer the lounge in Hilton Prague, but I like them both equally).
The lounge in Hilton Old Town is smaller and can feel a bit crowded at times. On the other hand, I find the staff in Old Town lounge to be friendlier.
Both lounges have wine and drinks.
Both hotels treat Diamonds well.
Hilton Old Town has a slightly better location but Hilton Prague is very close to a metro stop and a tram stop.